Cable-based heater and method of assembly

ABSTRACT

A cable-based heater for providing underground heat and a method of assembly of the cable-based heater are provided. The heater includes a length of coiled tubing having a sealed down-hole end and an open-ended cable support adapter attached to the up-hole end of the coiled tubing. One or more conducting cables are contained within the coiled tubing and a wedging tube is placed in the open end of the adapter for supporting the weight of the one or more cables against the interior sidewall of the adapter when the heater is deployed underground. The wedging tube has an inner surface shaped to conform to the outer shape of the one or more cables and an outer sidewall configured for weight bearing frictional contact with the interior sidewall of the cable support adapter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/730,371, filed on Jun. 4, 2015, which is a divisional of U.S. patentapplication Ser. No. 14/625,279 filed on Feb. 18, 2015, which claimspriority to U.S. Provisional Patent Application Ser. No. 61/941,251filed on Feb. 18, 2014 and U.S. Provisional Patent Application Ser. No.62/080,569 filed on Nov. 17, 2014, the entire disclosures of which areincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to the field of extraction of heavy oil andbitumen and more particularly to assembly of equipment used in processesinvolving heating of geological formations for the purpose of recoveryof heavy oil and bitumen.

BACKGROUND OF THE INVENTION

Heavy crude oil is closely related to natural bitumen from oil sandswith respect to a number of properties. Generally, bitumen is theheaviest, most viscous form of petroleum and is often referred to as“natural bitumen.” Bitumen shares the attributes of heavy oil but ismore dense and viscous. Natural bitumen and heavy oil differ from lightoils by having higher viscosity (resistance to flow) at reservoirtemperatures. As is known, heavy oil is often found at the margins ofgeologic basins and is thought to be the residue of formerly light oilthat has lost its light-molecular-weight components. Conventional heavyoil and bitumen differ in the degree by which they have been degradedfrom the original crude oil. Often, bitumen does not flow under ambientconditions within a given reservoir.

The large reserves of bitumen and heavy oil in the Alberta oil sandshave been under development for many years and the pace of developmentis accelerating. While certain areas of the oil sands are beingdeveloped by strip-mining due to the proximity of the bitumen to thesurface, many other areas where the bitumen is well below the surfaceare being developed using advanced processes which have a significantlylower impact on the landscape. One well known process is steam-assistedgravity drainage (SAGD) which typically utilizes two or more verticallydisplaced horizontal wells and high pressure steam that is continuouslyinjected into an upper wellbore to heat the reservoir. As a result, theviscosity of the heavy oil/bitumen within the reservoir is reduced,thereby enabling it to flow downward to a production well. Whileeffective, SAGD is energy intensive and requires significant surfaceinfrastructure to manage the steam production and water/oil recovery andseparation.

Another process for recovery of heavy oil and bitumen has been developedby the present applicant. This process, known as thermally-assistedgravity drainage (TAGD) has been described in US Patent Publication No.20120318512 which is incorporated herein by reference. In TAGD, alsousing horizontal wells, the mobility of the bitumen or heavy oil isincreased by conductive heating (instead of steam) to reduce itsviscosity. In these processes, the bitumen or heavy oil is heated totemperatures below the thermal cracking temperature of the bitumen orheavy oil. As the bitumen or heavy oil is produced, evolved gases,evaporated connate water or both form a gas chamber which acts toreplace the volume of the produced fluid required for the gravitydrainage process. Some of the more common applications of this processuse heaters placed in wells drilled in specific patterns surrounding themain producer well. The patterns have been developed by extensivereservoir modeling studies for optimizing placement of heaters foroptimal conduction of heat within the reservoir. These heaters arehereinafter referred to as “well heaters.” TAGD provides a number ofadvantages over SAGD processes including reduced energy and surfaceinfrastructure costs.

A number of other processes for recovery of heavy or bitumen are underdevelopment which will also require the use of well heaters. A number ofdifferent types of heating means may be provided in well heaters usedfor TAGD or other similar processes. Examples of such heating means mayinclude dielectric heating (also known as electronic heating, RF heatingand high frequency heating), hot water circulating heaters, catalyticheaters, fluid exchange heating, and heating using molten salts ormetals. One particularly useful class of well heating mechanism isresistance heating (also known as Joule heating and Ohmic heating). Thisheating mechanism is typically provided using cables with resistiveportions that release heat when subjected to electric currents. Theheater cables are typically run into wells using coiled tubing.

Because processes such as TAGD require heating of deep reservoirs, thelengths of the well heater cables and their protective components whichmake up the body of the heater (hereinafter referred to as well heaters)may be several thousand meters in length. A number of problems areassociated with assembly of such well heaters.

In the past, well heaters with resistive cables were assembled in areaswith very long sections of clear flat ground, such as unused aircraftrunways. Typically, a long section of coiled tubing would be unwoundonto the runway and secured to the ground using large heavy weights tomaintain the straightness of the coiled tubing. The heater cables wouldthen be pulled into the coiled tubing by inserting a tow cable throughthe coiled tubing and then pulling the heater cable through it. Afterthe components were assembled, the assembled heater would be spooledonto a standard coiled tubing reel and then transferred to the wells fordeployment. Not surprisingly, this method of assembling well heaters hassignificant drawbacks. For example, assembling a heater cable on adisused runway has significant risks, including the risk ofcontamination and/or damage to the cables as a result of dragging themover ground or pavement, safety risks associated with handling largeweights to safely secure the coiled tubing in a straight line, as wellas the practical limitation of identifying the required stretches ofclear flat ground or pavement. This method is also labor-intensive andwould typically require on the order of 25 workers about 6 days toassemble a single well heater. Furthermore, this assembly method is alsoaffected by the prevailing weather conditions.

Accordingly, there has been a need for improved systems and methods ofassembling heater cable systems and, in particular a need for systemsthat overcome the problems of assembling well heaters in an uncontrolledoutdoor environment.

More specifically, there has been a need for systems that enable thecontrolled “indoor” assembly of well heaters. In addition, there hasbeen a need for improved well heaters that can be readily assembled to adesired length with specific properties.

A review of the prior art indicates that various heater systems havebeen developed relating to various components of the heater systems andthe equipment required for handling and deployment of heater systems andcoiled tubing. For example, the construction of a “temperature limited”well heater is described in U.S. Pat. No. 8,579,031.

A gripper block for a coiled tubing injector with a variable tubing sizecapability is described in U.S. Pat. No. 6,892,810.

US Patent Publication No. 2010/0224368 describes a method for making acoiled insulated conductor heater to heat a subsurface formation. Themethod described in this reference includes the step of pushing theinsulated conductor heater longitudinally inside a flexible conduitusing pressure, wherein one or more cups are coupled to the outside ofthe insulated conductor heater. The cups are configured to maintain atleast some pressure inside at least a portion of the flexible conduit asthe insulated conductor heater is pushed inside the flexible conduit.

US Patent Publication No. 2010/0089584 describes a heater for treatingsubsurface formations which includes a conduit and three insulatedelectrical conductors located in the conduit.

US Patent Publication No. 2013/0086800 describes a process for forminginsulated conductor heaters using a powder as the insulator. The processincludes steps of feeding of sheath material such as stainless steel andconductor (core) material into a process flow line and passing thesecomponents through compression and centralizing rolls to form tubularmaterials, followed by addition of heated electrical insulator powderinto the sheath.

U.S. Pat. No. 8,502,120 describes an insulated conductor heater with anelectrical conductor that produces heat when an electrical current isprovided to the electrical conductor. An electrical insulator at leastpartially surrounds the electrical conductor. The electrical insulatorcomprises a resistivity that remains substantially constant, orincreases, over time when the electrical conductor produces heat.

US Patent Publication No. 2013/0118746 describes a system for use in anin situ oil production process which includes a multi-componentcomposite cable having multiple conductors for delivering electricalpower to a heater array, multiple hoses for transmitting fluid to aheater array, a strength member made of a heat resistant synthetic fibermaterial, and a cable jacket layer surrounding the conductors, hoses andstrength member.

U.S. Pat. No. 4,570,715 describes an electrical heater containingspoolable, steel sheathed, mineral insulated cables which have highelectrical conductivities. The conductors are surrounded by heat stableelectrical insulations such as a mass of compacted powdered mineralparticles and/or by discs of ceramic materials.

In view of the foregoing, there continues to be a need for improved wellheater systems and processes for assembly of these well heaters.

SUMMARY OF THE INVENTION

One aspect of the invention is a method for assembly of a well heater,the method comprising: a) injecting a length of coiled tubing into awell, supporting the coiled tubing in the well and cutting the coiledtubing above the well head; b) injecting one or more resistive heatingcables into the into the coiled tubing; c) constructing a cable supportstructure at the cut end of the coiled tubing for supporting the weightof the cables against the inner sidewall of the coiled tubing; d)cutting the cables and configuring the cut ends of the cables forconnection to an electrical source, thereby defining the structure ofthe well heater; and e) withdrawing the well heater from the well.

In certain embodiments, the well is a vertical well or a deviated well.

In certain embodiments, the deviated well is deviated from vertical bybetween about 30 degrees to about 50 degrees.

In certain embodiments, the deviated well is deviated from vertical bybetween about 35 to about 45 degrees.

In certain embodiments, step b) includes injection of three resistiveheating cables which are connected at the injected end by a wye splice.

In certain embodiments, the three resistive heating cables areconfigured for transmission of three-phase electrical power.

In certain embodiments, step a) includes attaching a cover to theinjected end of the coiled tubing.

In certain embodiments, the method further comprises attaching one ormore temperature measurement lines to one or more of the cables andinjecting the temperature measurement lines into the coiled tubingtogether with the cables.

In certain embodiments, the temperature measurement lines include athermocouple line or a fiber optic line configured for distributedtemperature sensing.

In certain embodiments, the temperature measurement lines include atleast one thermocouple line and at least one fiber optic line configuredfor distributed temperature sensing.

In certain embodiments, the method further includes as step f) a processof reeling the well heater onto a coiled tubing reel.

Another aspect of the invention is a facility for assembly of wellheaters, the facility comprising: a) a well of sufficient diameter toreceive coiled tubing; b) a scaffold supporting a coiled tubinginjector, wherein the injector is configurable for injection of coiledtubing into the well and configurable for injection of one or moreresistive heating cables into coiled tubing in the well; c) a coiledtubing guide system supported by the injector or the scaffold; and d)one or more cable guides for guiding the resistive heating cables fromrespective cable reels into the injector, wherein the cable guides aresupported by the scaffold.

In certain embodiments, the well is a vertical well or a deviated well.

In certain embodiments, the deviated well is deviated from vertical bybetween about 30 degrees to about 50 degrees.

In certain embodiments, the deviated well is deviated from vertical bybetween about 35 to about 45 degrees.

In certain embodiments, at least part of the coiled tubing guide is agooseneck connected to the injector.

In certain embodiments, the one or more cable guides are guide sheavessupported by a beam of the scaffold.

In certain embodiments, the scaffold includes a first platform forworkers to obtain access to the injector.

In certain embodiments, the scaffold includes a second platform forworkers to obtain access to the top of the injector and to the guidesheaves supported by the upper beam of the scaffold.

In certain embodiments, the facility further comprises a coveredstructure to provide protection of the facility from weather elements.

In certain embodiments, the injection system is configured to allowexchange of coiled tubing gripper blocks for gripper blocks configuredfor simultaneous injection of one or more cables.

In certain embodiments, the facility further comprises a coiled tubingstraightener and a cable straightener, each supported by the scaffold.

In certain embodiments, the cable straightener is configured tostraighten three cables simultaneously.

In certain embodiments, the coiled tubing straightener is supported bythe scaffold below the cable straightener and the cable straightenerincludes swivel means to remove the cable straightener from the path ofentry of the coiled tubing into the injector.

In certain embodiments, the facility further comprises a crane fortransferring an assembled well heater spooled on a reel to a deliveryvehicle.

In certain embodiments, the covered structure includes a bay opening toallow access of a delivery vehicle to the interior of the coveredstructure.

Another aspect of the invention is a method of retrofitting a coiledtubing injector for injection of resistive heating cables, the methodcomprising: a) providing a coiled tubing injector with a gripper blocksystem that allows exchange of the coiled tubing gripper blocks; and b)exchanging coiled tubing gripper blocks for cable gripper blocks.

In certain embodiments, the cable gripper blocks each include threeindentations for gripping three resistive heating cables.

Another aspect of the present invention is a method for injecting cablesinto a well or into coiled tubing deployed in a well, the methodcomprising: a) providing a coiled tubing injector above the well, thecoiled tubing injector having coiled tubing gripper blocks replaced withcable gripper blocks; b) guiding one or more cables from respectivecable reels into the top of the injector; and c) using the injector toinject the cables into the well or into the coiled tubing deployed inthe well with downward vertical movement of the cables driven bygripping and downward vertical movement of the cable gripper blocks.

In certain embodiments, a cable straightener is provided above thecoiled tubing injector for straightening of the cables prior to entry ofthe cables into the top of the injector.

In certain embodiments, the cable straightener is provided with swivelmeans to move it laterally from a position directly above the injector.

In certain embodiments, the cable gripper blocks are configured tosimultaneously grip three cables.

In certain embodiments, the cable gripper blocks each have threeindentations, wherein each indentation holds one of the three cables.

In certain embodiments, the indentations are each radiused to holdcables having an outer diameter of about 0.85 inches.

Another aspect of the present invention is a cable gripper block for usein retrofitting a coiled tubing injector for simultaneous injection ofthree cables into a well or into coiled tubing deployed in a well, thegripper block comprising: a) a cable gripping side with threeindentations, each indentation for gripping one of the three cables; andb) an opposite side having a means for attachment of the gripper blockto a drive mechanism of a coiled tubing injector.

In certain embodiments, the means for attachment of the gripper block tothe drive mechanism is a groove which couples to a ridge on the drivemechanism or a ridge which couples to a groove on the drive mechanism.

In certain embodiments, the indentations are each radiused to holdcables having an outer diameter of about 0.85 inches.

Another aspect of the invention is a kit for use in retrofitting acoiled tubing injector for injection of cables into a well or intocoiled tubing deployed in a well, the kit comprising: a set of cablegripper blocks wherein each cable gripper block of the set is a squareor rectangular block having: i) a cable gripping side with threeindentations, each indentation for gripping one of the three cables; andii) an opposing side opposite the gripping side, the opposing sidehaving a means for attachment of the gripper block to a drive mechanismof a coiled tubing injector.

In certain embodiments, the means for attachment of the cable gripperblock to the drive mechanism is a groove which couples to a ridge on thedrive mechanism or a ridge which couples to a groove on the drivemechanism.

In certain embodiments, the indentations are each radiused to holdcables having an outer diameter of about 0.85 inches.

In certain embodiments, the further comprises instructions for replacingthe gripper blocks of a coiled tubing injector with the set of gripperblocks.

Another aspect of the present invention is a resistive cable-based wellheater for providing heat to an oil or gas bearing formation, the wellheater comprising: a) a length of coiled tubing having a sealeddown-hole end and an open-ended cable support adapter attached to theup-hole end of the coiled tubing; b) a bundle of cables contained withinthe coiled tubing and conductively connected to each other at theirdown-hole ends at a location above the sealed down hole end of thecoiled tubing, the cables extending from the upper opening of the cablesupport adapter and having free upper ends; and c) a wedging tube placedin the open end of the adapter for supporting the weight of the cablesagainst the interior sidewall of the adapter when the well heater isdeployed in a well, the wedging tube having an inner surface shaped toconform to the outer shape of the bundle of cables and an outer sidewallconfigured for weight bearing frictional contact with the interiorsidewall of the cable support adapter.

In certain embodiments, attachment of the adapter to the coiled tubingis by welding.

In certain embodiments, the bundle of cables consists of three cables,each having a core and a sheath, with insulation therebetween.

In certain embodiments, the three cables are conductively connected by awye-splice connector.

In certain embodiments, the wye splice connector includes an end plateconnected to the sheath of each of the three cables with the core ofeach of the cables protruding outward therefrom, the end of the core ofeach of the three cables connected to respective openings in a connectordisk.

In certain embodiments, the connection of the sheath of each cable tothe end plate is made by welding and the connection between the end ofeach cable core and the connector disk is made by welding.

In certain embodiments, the wye splice is covered with a substantiallycylindrical cover and the space between the wye splice and the innersidewall of the cylindrical cover is filled with powder insulation.

In certain embodiments, the powder insulation is MgO.

In certain embodiments, the cables each have at least one portion havingresistivity for providing heat when an electrical current is provided tothe cables.

In certain embodiments, the cables each have a copper core with astainless steel sheath and insulation disposed therebetween.

In certain embodiments, the insulation is MgO.

In certain embodiments, the free upper ends of the cables are insulatedby a hollow plastic insulating cable insert having a first portiondisposed between the inner sidewall of the sheath and the outer sidewallof the core of each cable, the insulating cable insert having a secondportion extending out from the end of the sheath, wherein a length ofthe core of each cable extends outward from the hollow interior of theinsert.

In certain embodiments, the outer sidewall of the insulating cableinsert is fixed to the inner sidewall of the sheath with epoxy resin.

In certain embodiments, the plastic insert is formed of polyether etherketone (PEEK).

In certain embodiments, the end of the first portion of the insert istapered.

In certain embodiments, the adapter is cylindrical.

In certain embodiments, the well heater further comprises an open endedcylindrical retaining sleeve attached to the upper end of the adapter.

In certain embodiments, the retaining sleeve has inner threads whichcouple with outer threads on the adapter.

In certain embodiments, the well heater further comprises at least onetemperature measurement line for providing temperature measurements atone or more points along the length of the well heater, wherein thetemperature measurement line is attached to the bundle of cables.

In certain embodiments, the well heater further comprises one or morethermocouple lines for making one or more spot temperature measurementsat one or more locations along the length of the cables and a fiberoptic line for distributed temperature sensing.

In certain embodiments, the wedging tube includes one or morelongitudinal slots.

In certain embodiments, the wedging tube includes four equi-spacedlongitudinal slots.

In certain embodiments, the wedging tube includes three transverse slotswhich define an interior solid triangular portion.

In certain embodiments, the wedging tube includes six transverse slotsformed from three sets of two parallel transverse slots which define aninterior solid triangular portion.

In certain embodiments, the interior solid triangular portion hastriangle tips which extend to the outer circumference of the wedgingtube.

In certain embodiments, the interior solid triangular portion hastriangle tips which are recessed inside the outer circumference of thewedging tube.

In certain embodiments, the wedging tube is formed from three separatewedging tube segments, each having an inner surface configured toconform to the shape of a portion of the bundle of cables.

In certain embodiments, at least one of the three wedging tube segmentsincludes an opening to allow passage of a temperature line therethrough.

In certain embodiments, two of the wedging tube segments include anopening to allow passage of a temperature line therethrough.

In certain embodiments, the well heater further comprises a removableretaining sleeve attached to the adapter.

In certain embodiments, the well heater further comprises a removableprotective cover attached to the retaining sleeve.

In certain embodiments, the protective cover has inner threads whichcouple with outer threads on the top of the retaining sleeve.

Another aspect of the invention is a well heater product in compact formfor transport to a deployment site, the product comprising the wellheater as described herein spooled on a coiled tubing reel.

In certain embodiments, the coiled tubing reel includes a start hole forinsertion of the up-hole end of the assembled heater, and a curved rampis connected to or integrally formed with the reel adjacent to the starthole on an emergent side of the start hole.

Another aspect of the invention is a method for constructing a resistivecable-based well heater for providing heat to an oil or gas bearingformation, the method comprising: a) injecting a length of coiled tubingwith a sealed down-hole end into a vertical or deviated well; b)supporting the coiled tubing at the well head and cutting the coiledtubing above the well head; c) attaching an open ended cable supportadapter having an upper platform surface to the cut end of the coiledtubing; d) injecting a cable bundle through the adapter into the coiledtubing, wherein the cables of the cable bundle are conductivelyconnected to each other at the downhole end and wherein individualcables are deployed from individual corresponding spools; e) attaching acable bundle clamp having a lower flat surface to the cables above theadapter; f) injecting the cable bundle further downward into the coiledtubing to place the lower flat surface of the cable bundle clamp uponthe upper platform surface of the cable support adapter; g) cutting thecables of the cable bundle from their respective spools above the cablebundle clamp, thereby transferring the support of the weight of thecable bundle from the spools to the cable bundle clamp and the cablesupport adapter; h) attaching a wedging tube carrier carrying areversibly connected wedging tube to the wedging tube carrier to thecable bundle above the cable bundle clamp, the wedging tube having aninner surface shaped to conform to the shape of the cable bundle and anouter curved surface configured for substantive weight bearingfrictional contact with the inner sidewall of the cable support adapter;i) connecting a lifter to the wedging tube carrier and raising the cablebundle using the lifter; j) removing the cable bundle clamp from thecable bundle; k) lowering the cable bundle using the lifter to insertthe wedging tube into the adapter to grip the cable bundle and bring thewedging tube into substantive weight bearing frictional contact with theinner sidewall of the adapter; and l) removing the wedging tube carrierfrom the cable bundle and the wedging tube.

In certain embodiments, the cable support adapter is attached to thecoiled tubing by welding.

In certain embodiments, the bundle of cables consists of three cables,each having a core and a sheath, with insulation therebetween.

In certain embodiments, the three cables are conductively connected by awye-splice connector.

In certain embodiments, the wye splice connector includes an end plateconnected to the sheath of each of the three cables with the core ofeach of the cables protruding outward therefrom, the end of the core ofeach of the three cables connected to respective openings in a connectordisk.

In certain embodiments, the connection of the sheath of each cable tothe end plate is made by welding and the connection between the end ofeach cable core and the connector disk is made by welding.

In certain embodiments, the wye splice is covered with a substantiallycylindrical cover and the space between the wye splice and the innersidewall of the cylindrical cover is filled with powder insulation.

In certain embodiments, the powder insulation is MgO.

In certain embodiments, the cables each have at least one portion havingresistivity for providing heat when an electrical current is provided tothe cables.

In certain embodiments, the cables each have a copper core withstainless steel sheath and insulation disposed therebetween.

In certain embodiments, the insulation is MgO.

In certain embodiments, the method further comprises the step ofproviding protective insulation at the cut ends of the cables.

In certain embodiments, the protective insulation is provided by ahollow plastic insulating cable insert having a first portion disposedbetween the inner sidewall of the sheath and the outer sidewall of thecore of each cable, the insulating cable insert having a second portionextending out from the end of the sheath, wherein a length of the coreof each cable extends outward from the hollow interior of the insert.

In certain embodiments, the outer sidewall of the insulating cableinsert is fixed to the inner sidewall of the sheath with epoxy resin.

In certain embodiments, the plastic insulating cable insert is formed ofpolyether ether ketone (PEEK).

In certain embodiments, the end of the first portion of the insulatingcable insert is tapered.

In certain embodiments, the adapter is cylindrical.

In certain embodiments, the method further comprises attaching an openended cylindrical retaining sleeve to the upper end of the adapter forholding the wedging tube in place against the inner sidewall of theadapter and against the cables.

In certain embodiments, the retaining sleeve has inner threads whichcouple with outer threads on the adapter.

In certain embodiments, the method further comprises attaching at leastone temperature measurement line to the bundle of cables beforeinjection of the cables into the coiled tubing, the temperaturemeasurement line for providing temperature measurements at one or morepoints along the length of the well heater.

In certain embodiments, the method further comprises attaching one ormore thermocouple lines and a fiber optic line to the bundle of cablesbefore injection of the cables into the coiled tubing, the thermocouplelines for making one or more spot temperature measurements at one ormore locations along the length of the cables and the fiber optic linefor distributed temperature sensing.

In certain embodiments, the wedging tube includes one or morelongitudinal slots.

In certain embodiments, the wedging tube includes four equi-spacedlongitudinal slots.

In certain embodiments, the wedging tube includes three transverse slotswhich define an interior solid triangular portion.

In certain embodiments, the wedging tube includes six transverse slotsformed from three sets of two parallel transverse slots which define aninterior solid triangular portion.

In certain embodiments, the interior solid triangular portion hastriangle tips which extend to the outer circumference of the wedgingtube.

In certain embodiments, the interior solid triangular portion hastriangle tips which are recessed inside the outer circumference of thewedging tube.

In certain embodiments, the wedging tube is formed from three separatewedging tube segments, each having an inner surfaces configured toconform to the shape of a portion of the bundle of cables.

In certain embodiments, at least one of the three wedging tube segmentsincludes an opening to allow passage of a temperature line therethrough.

In certain embodiments, two of the wedging tube segments include anopening to allow passage of a temperature line therethrough.

In certain embodiments, the method further comprises attaching aremovable retaining sleeve to the adapter.

In certain embodiments, the method further comprises attaching aremovable protective cover to the retaining sleeve.

In certain embodiments, the protective cover has inner threads whichcouple with outer threads on the top of the retaining sleeve.

In certain embodiments, the method further comprises the step ofwithdrawing the assembled well heater from the well and spooling thewell heater onto a coiled tubing reel for storage or transport to adeployment site.

In certain embodiments, the coiled tubing reel includes a start hole forinsertion of the up-hole end of the assembled heater and a curved rampis connected to or integrally formed with the reel adjacent to the starthole on an emergent side of the start hole.

In certain embodiments, the cable support adapter is initiallyconstructed from a set of components comprising: i) a permanentopen-ended cylinder configured to fit to the end of the coiled tubing;ii) a temporary lateral surface extension clamp configured to clamp tothe outer sidewall of the open-ended cylinder; and iii) a temporaryc-shaped extension platform with a lower c-shaped flat surfaceconfigured to rest upon the upper surface of the lateral extension clampand an upper c-shaped flat surface which provides the upper platformsurface.

In certain embodiments, the lateral extension clamp and the extensionplatform are removed together with removal of the cable bundle clamp instep j).

In certain embodiments, the open-ended cylinder has a circumferentialgroove and the lateral extension clamp has an inner ridge that is placedinside the groove to provide additional clamping support when thelateral extension clamp is clamped to the cylinder.

In certain embodiments, the extension platform is provided with sidehandles to facilitate manual transport.

In certain embodiments, the cable bundle clamp comprises: i) a pair ofgripper blocks with inner surfaces configured to conform to the outersurfaces of the cable bundle; and ii) a central gripping memberconfigured to conform to the inner surfaces of the cable bundle when thecable bundle is gripped by the cable bundle clamp.

In certain embodiments, the wedging tube carrier comprises: i) a pair ofreversibly connectable cylinder halves each having a lower lip portionto which the wedging tube is reversibly attached when the wedging tubecarrier is connected to the cables; and ii) an upper portion configuredfor attachment to a cap having a means for connecting to the lifter.

In certain embodiments, the wedging tube carrier comprises a secondwedging tube placed between the inner sidewall of the connected cylinderhalves and the cables, the second wedging tube having an inner surfaceshaped to conform to the shape of one or more of the cables and an outersurface configured for substantive weight bearing frictional contactwith the inner sidewalls of the pair of cylinder halves.

In certain embodiments, the second wedging tube is identical to thewedging tube recited in step h).

Another aspect of the invention is a method for supporting a bundle ofcables in a well or in a length of coiled tubing deployed in a verticalor deviated well during a process for assembly of a well heater whichincludes steps of injecting the cables from respective spools into thecoiled tubing, the method comprising: a) attaching an open-ended cablesupport adapter to the up-hole end of the coiled tubing, the adapterhaving an upper flat surface extending laterally outward from the outerdiameter of the coiled tubing; b) attaching a cable bundle clamp havinga lower flat surface to the bundle of cables above the cable supportadapter; c) injecting the cables further downward into the coiled tubingso that the lower flat surface of the cable bundle clamp rests upon theupper flat surface of the cable support adapter; d) cutting the cablesfrom their respective spools above the cable bundle clamp, therebytransferring the support of the weight of the deployed cables from thespools to the cable bundle clamp and the adapter; e) clamping a wedgingtube carrier to the cable bundle above the cable bundle clamp, thewedging tube carrier having a wedging tube reversibly attached to itslower end, the wedging tube having an inner surface shaped to conform tothe shape of one or more of the cables and an outer surface configuredfor weight bearing frictional contact with the inner sidewall of thecable support adapter; f) connecting a lifter to the wedging tubecarrier and raising the cable bundle using the lifter; g) removing thecable bundle clamp from the cable bundle; h) lowering the cables usingthe lifter to insert the wedging tube into the adapter to bring theminto substantive weight bearing frictional contact with the innersidewall of the adapter; and i) removing the wedging tube carrier fromthe bundle of cables.

In certain embodiments, the cable support adapter is initiallyconstructed from a set of components comprising: i) a permanentopen-ended cylinder configured to fit to the end of the coiled tubing,ii) a temporary lateral surface extension clamp configured to clamp tothe outer sidewall of the open-ended cylinder; and iii) a temporaryc-shaped extension platform with a lower c-shaped flat surfaceconfigured to rest upon the upper surface of the lateral extension clampand an upper c-shaped flat surface which provides the upper platformsurface.

In certain embodiments, the lateral extension clamp and the extensionplatform are removed with removal of the cable bundle clamp in step g).

In certain embodiments, the open-ended cylinder has a circumferentialgroove and the lateral extension clamp has an inner ridge that is placedinside the groove to provide additional clamping support when thelateral extension clamp is clamped to the cylinder.

In certain embodiments, the extension platform is provided with sidehandles to facilitate manual transport.

In certain embodiments, the bundle of cables comprises three cables andthe cable bundle clamp comprises: i) a pair of gripper blocks with innersurfaces configured to conform to the outer surfaces of the bundle ofcables; and ii) a central gripping member configured to conform to theinner surfaces of the cable bundle when the bundle of cables is grippedby the cable bundle clamp.

In certain embodiments, the wedging tube carrier comprises: i) a pair ofreversibly connectable cylinder halves each having a lower lip portionto which the wedging tube is reversibly attached when the wedging tubecarrier is connected to the cables; and ii) an upper portion configuredfor attachment to a cap having a means for connecting to the lifter.

In certain embodiments, the wedging tube carrier comprises a secondwedging tube placed between the cables and the inner sidewall formed byconnection of the cylinder halves, the second wedging tube having aninner surface shaped to conform to the shape of one or more of thecables and an outer surface configured for substantive weight bearingfrictional contact with the inner sidewall formed by connection of thecylinder halves.

In certain embodiments, the second wedging tube is identical to thewedging tube recited in step e).

Another aspect of the invention is an insulating cable insert forprotection of a cut end of a cable having a sheath and a conductingcore, the insert comprising a cylindrical body with a hollow spaceextending therethrough, the body having a first end portion configuredto fit in the space between the core and the sheath of the cable and asecond portion wider than the first portion configured to extend outwardfrom the end of the sheath when the insert is installed.

In certain embodiments, the insert is formed of plastic.

In certain embodiments, the plastic is polyether ether ketone (PEEK).

In certain embodiments, the end of the first portion of the insert istapered.

In certain embodiments, the hollow space has a diameter greater thanabout 0.394 inches.

In certain embodiments, the second portion has an outer diameter greaterthan about 0.85 inches.

In certain embodiments, the insulating cable insert has a total lengthof about 2.2 inches.

Another aspect of the invention is a kit for providing insulatingprotection to a cut end of a conducting cable, the kit comprising: a) aninsulating cable insert, the insert comprising a cylindrical body with ahollow space extending therethrough, the body having a first end portionconfigured to fit in the space between the core and the sheath of thecable and a second portion wider than the first portion configured toextend outward from the end of the sheath when the insert is installed;and b) a hollow drill bit configured to remove insulation from the spacebetween the core and the sheath of the cable.

In certain embodiments, the kit further comprises a second hollow drillbit configured to polish the inner sidewall of the sheath of the cable.

In certain embodiments, the kit further comprises an epoxy resin forfixing the insert to the space between the cable sheath and the cablecore.

In certain embodiments, the kit further comprises a clamp for providingpressure to the sheath and to the top of the insert when the insert isinstalled with an adhesive between the cable sheath and the cable core.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the accompanying figures inwhich:

FIG. 1 is a schematic elevation view of an assembly facility 10according to one embodiment of the present invention.

FIG. 2 is a schematic plan view of another embodiment of an assemblyfacility 100 in accordance with one embodiment of the present invention.

FIG. 3 is a schematic cross sectional view of a well heater 200according to one embodiment of the invention.

FIG. 4A is a perspective partially exploded view of the layers of amineral-insulated conducting cable C used in certain embodiments of thepresent invention.

FIG. 4B is a cross section taken across plane 4B of FIG. 2A.

FIG. 5A is a perspective view of the wye-splice 400 and detached wyesplice cover 406 according to one embodiment of the present invention.

FIG. 5B is a perspective view of the same embodiment of FIG. 5A with thewye splice cover 406 (partially transparent in this view) installedagainst the end plate 402 of the wye splice 400.

FIG. 5C is a perspective view of the connector disk 404 component of thewye splice 400 shown prior to installation.

FIG. 5D is a perspective view of the end plate 402 component of the wyesplice 400 shown prior to installation.

FIG. 6A is a perspective view of a cable support adapter 501 accordingto one embodiment of the present invention.

FIG. 6B is a perspective view of a cable support adapter 501 installedat the up-hole end of a length of coiled tubing CT and showing cablesC-1, C-2 and C-3 supported by the combination of a cable bundle clamp511 and the cable support adapter 501.

FIG. 7A is a perspective view of a receptacle 600 which forms part ofanother embodiment of a cable support adapter.

FIG. 7B is an exploded view of a lateral extension clamp 620 which,together with the receptacle 600 of FIG. 7A, and the extension platform640 of FIG. 7C forms part of an embodiment of a cable support adapter.

FIG. 7C is a perspective view of an extension platform 640 which,together with the receptacle 600 of FIG. 7A, and the lateral extensionclamp 620 of FIG. 7B, forms an embodiment of a cable support adapter.

FIG. 8A is a perspective view of a cable bundle clamp 650 which togetherwith the cable support adapter components of FIGS. 7A to 7C forms atemporary cable support assembly.

FIG. 8B is a top view of the cable bundle clamp 650 of FIG. 8A showingthe central gripping member 656.

FIG. 8C is a perspective view of the central gripping member 656 of thecable bundle clamp 650.

FIG. 9 is an exploded view of the temporary cable support assemblyformed of the components of FIGS. 7 and 8.

FIG. 10 is a side elevation view of the temporary cable support assemblyformed of the components of FIGS. 7 and 8.

FIG. 11A is a perspective view of one embodiment of a wedging tube 705with longitudinal slots showing detail of its up-hole end.

FIG. 11B is a perspective view of the embodiment of the wedging tube 705of FIG. 11A with equi-spaced longitudinal slots showing detail of itsdown-hole end.

FIG. 12A is a perspective view of a second embodiment of a wedging tube725 with transverse slots showing detail of its up-hole end.

FIG. 12B is a perspective view of the wedging tube 725 of FIG. 12A withtransverse slots showing detail of its down-hole end.

FIG. 13A is perspective view of a third embodiment of a wedging tube 745with two sets of parallel transverse slots showing detail of itsdown-hole end.

FIG. 13B is an end view of the down-hole end of the wedging tube 745 ofFIG. 13A with two sets of parallel transverse slots showing detail ofits down-hole end.

FIG. 13C is a magnified view of the upper circle of FIG. 13B showingdetail of the triangle tip 759 a of wedging tube 745.

FIG. 14A is perspective view of a fourth embodiment of a wedging tube765 with two sets of parallel transverse slots showing detail of itsdown-hole end.

FIG. 14B is an end view of the down-hole end of the wedging tube 765 ofFIG. 14A with two sets of parallel transverse slots showing detail ofits down-hole end.

FIG. 14C is a magnified view of the upper circle of FIG. 14B showingdetail of the recessed triangle tip 779 a of wedging tube 765.

FIG. 15A is a perspective view of a set of wedging tube segments 785 a,785 b and 785 c which, when assembled as shown in FIG. 15B form a fifthwedging tube embodiment.

FIG. 15B is a perspective view of the assembled fifth wedging tubeembodiment.

FIG. 16 is a partially exploded view showing the arrangement of thewedging tube 705, cables C-1, C-2 and C-3, thermocouple line TH andfiber optic line FO prior to insertion into the receptacle 600. Thearrow shows the direction of insertion.

FIG. 17A is a perspective view of the assembled wedging tube carrier700.

FIG. 17B is a side elevation view of the wedging tube carrier 700showing the lower lip 710 which is used as a point of connection to awedging tube (not shown).

FIG. 18 is an exploded view of the components of the wedging tubecarrier 700 and other components associated therewith, as used duringthe process of inserting the wedging tube 705 and cable bundle (notshown) into the receptacle (not shown). Two wedging tubes 705 a and 705b are used with wedging tube 705 b being connected to the lip 710 forinsertion into the receptacle.

FIG. 19 is a side elevation view of the assembled components associatedwith the wedging tube carrier 700 and the temporary cable support systemcomprised of the cable bundle clamp 650 and the components of the cablesupport adapter including the receptacle 600, the lateral extensionclamp 620 and the extension platform 640.

FIG. 20 is a side elevation view of the assembled components associatedwith the wedging tube carrier 700 (including the lifting means L) afterremoval of the cable bundle clamp 650 and the extension platform 640.Although the lateral extension clamp 620 is shown, its presence at thisstage is optional.

FIG. 21A is a perspective view of a wedging tube seating tool 810 whichfits over the cut ends of the cables (not shown) and threads onto theupper outer threads of the receptacle (not shown).

FIG. 21B is a cross sectional view of the wedging tube seating tool 810of FIG. 21A taken along plane 16B showing inner threads 816 and an innerridge 818.

FIG. 22A is a perspective view of a cylindrical sleeve 850 configured tothread onto the outer lower threads of the receptacle (not shown).

FIG. 22B is a cross sectional view of the cylindrical sleeve 850 of FIG.22A taken along plane 22B.

FIG. 23 is an exploded view of the permanent cable support system whichis constructed of the receptacle 600 and wedging tube 705 in combinationwith the protective sleeve 850 of FIGS. 22A and 22B and protective cover860.

FIG. 24A is a perspective view of an insulating cable insert 900.

FIG. 24B is a side elevation view of the insulating cable insert 900 ofFIG. 24A with dotted lines showing the diameter of the hollow space 902.

FIG. 25 is a perspective view showing how the insulating cable insert900 fits over the conducting core 302 and into the space which is formedbetween the core 302 and the cable sheath 306 after removal of theinsulating layer of the cable. The arrow shows the direction of movementof the insulating cable insert 900 during installation with the taperedportion 904 facing downwards.

FIG. 26 is a side elevation view of a known arrangement of a coiledtubing injector 20 showing the injector drive 36 and coiled tubinggripper blocks 950 a, 950 b, 950 c, 950 d and 950 e

FIG. 27 is a side elevation view of a coiled tubing injector 20retrofitted for injection of cables (not shown), showing the injectordrive 36 and cable gripper blocks 970 a, 970 b, 970 c, 970 d and 970 eaccording to an embodiment of the present invention.

FIG. 28 is a partial perspective view of the two sides of an injectordrive 36 of a coiled tubing injector and pairs of cable gripper blocks(970 a/971 a and 970 b/971 b) connected thereto. This view shows how thecables C-1, C-2 and C-3 are gripped by the two pairs of cable gripperblocks 970 a/971 a and 970 b/971 b.

FIG. 29A is a perspective view of a cable gripper block 970 a.

FIG. 29B is a top view of the cable gripper block of FIG. 29A showingthe back wall 979 with a connector 981 attached thereto for connectionto the injector drive mechanism (not shown). Also shown in this view arethe three indentations 978 a, 978 b, and 978 c which are used to gripthe cables in combination with a second gripper block as shown in FIG.28.

DETAILED DESCRIPTION OF THE INVENTION

Various aspects of the invention will now be described with reference tothe figures. For the purposes of illustration, components depicted inthe figures are not necessarily drawn to scale. Instead, emphasis isplaced on highlighting the various contributions of the components tothe functionality of various aspects of the invention. A number ofalternative features are introduced in context of certain aspects of theinvention during the course of this description. It is to be understoodthat such alternative features may be substituted in variouscombinations to arrive at different embodiments of the presentinvention.

Operational and Assembly Overview

The invention generally relates to systems and methods for the assemblyof down-hole electric heating systems within a previously-drilled wellwhich is designed for the assembly of such heating systems. The electricheating systems or well heaters include specialized lengths of resistiveheating cables that, after assembly and when deployed in a TAGD well (orin another well heating application), provide the means to electricallyheat a reservoir to enhance the process of hydrocarbon recovery.Generally, the method of assembling the well heaters involves thesequenced insertion and assembly of well heater components within anassembly well and the subsequent removal of the assembled well heaterfrom the assembly well for transportation to the site of deployment.

The assembly of a well heater within an assembly well includes a numberof general steps. Each of these steps are conducted to ensure the safehandling of the well heater components and specifically to ensure thatthe weight of each of the well heater components are properly supportedat surface to enable surface assembly operations to be completed.

-   -   a. a length of coiled tubing is run into the assembly well        through a well head using a coiled tubing injector;    -   b. the coiled tubing is supported at the well head using a        conventional coiled tubing support system;    -   c. the coiled tubing is cut above the coiled tubing support        system and well head;    -   d. a cable support adapter is attached to the upper end of the        coiled tubing;    -   e. the downhole ends of heater cables are electrically connected        together at surface;    -   f. the connected heater cables are drawn through the coiled        tubing injector (which is retrofitted for injection of cables        instead of coiled tubing) and run down within the coiled tubing        to a desired distance (length) using the coiled tubing injector;    -   g. a first temporary cable support system is engaged with the        heater cables which protrude from the well head;    -   h. the heater cables are cut above the temporary support system;    -   i. the ends of the heater cables are protected with an insulated        cable insert and configured for ultimate connection to the power        supply at deployment;    -   j. a second temporary support system and a permanent support        system are engaged adjacent to the upper ends of the heater        cables above the first temporary support system;    -   k. the heater cables are lifted to enable removal of the first        temporary support system;    -   l. the heater cables are lowered to engage the permanent support        system within the cable support adapter;    -   m. the second temporary support system is removed;    -   n. a protective cover is connected to the upper end of the cable        support adapter to form an assembled well heater; and    -   o. the assembled well heater is removed from the assembly well        and spooled onto a coiled tubing reel for transportation.

Additional description relating to each of these steps is providedhereinbelow.

Overview of an Embodiment of a Well Heater Assembly Facility

In FIG. 1, there is shown a schematic view of one embodiment of afacility for assembly of well heaters. The components of the facility 10are not drawn to scale but are instead drawn to emphasize certainfeatures of the facility 10. Features of the finished well heaterassembled using the facility 10 and process of the present invention aredescribed in more detail hereinbelow. Advantageously in certainembodiments, the facility 10 is enclosed by a covering structure such asa shed or hangar (not shown) which provides shelter of the components ofthe facility from the elements. The facility therefore may be consideredpermanent or semi-permanent. However, it is possible to rapidlyconstruct similar facilities with convenient access to geologicalformation sites which are to be heat-treated using well heaters andprocesses such as steam-assisted gravity drainage (SAGD) or inthermally-assisted gravity drainage (TAGD) for recovery of heavy oil orbitumen, as described, for example, in US Application No. 20120318512(incorporated herein by reference in entirety). Such sites willtypically require several well heaters to heat a geological formationand it is the purpose of the facility 10 to produce the well heaters inan efficient and reproducible manner to address this need.

The facility 10 is located at the site of a well 12 (in this particularembodiment, a deviated well) which in most cases would have been drilledprior to the construction of the facility 10 whereupon the drillingequipment is removed from the site prior to construction of the rest ofthe facility 10. The well 12 is hereinafter designated an “assemblywell,” most notably because it is for assembly of well heaters and notfor recovery of hydrocarbons. In certain embodiments, when the lengthsof the well heaters are relatively short (and the cumulative weight ofthe cables and coiled tubing is relatively light), a simple verticalassembly well may be used. In other facility embodiments, which are usedto assemble longer well heaters, the cumulative weight of the cables istoo great to allow them to simply hang in a vertical well and the forceof gravity acting on the cumulative weight will result in excessivestress acting on the cable support system, possibly leading todeformation or breakage of components of the well heater and/or thesupport system. Therefore, in such embodiments, it is advantageous touse a deviated well, which reduces the force and stresses induced bygravity acting on the cumulative weight of the cables and coiled tubing.In certain embodiments, the deviation of the deviated assembly well 12is by about 30 to about 50 degrees from vertical or by about 35 to about45 degrees from vertical.

Advantageously, the well is lined with a casing cemented in placeaccording to conventional methods. In certain embodiments, an additionalcasing liner (not shown) is provided to prevent damage to the casingwhich is expected to occur with the friction associated with repeatedinsertion and withdrawal of well heaters and components thereof. Incertain embodiments, the casing liner is configured with a means forwithdrawing it from the well casing so that it can be replaced. Thecasing liner may be formed of a material less durable than the coiledtubing material, (such as aluminum or plastic, for example) so that thecoiled tubing structural integrity is maintained at the expense of thecasing liner.

It is seen in FIG. 1 that a scaffold 14 is erected above the wellhead 16of the deviated assembly well 12 to support certain components of thefacility 10 as described below.

Advantageously, the scaffold 14 is assembled to provide a work window 18to allow access of workers and equipment to the wellhead 16 forperformance of various well heater assembly and maintenance tasks. Inthe particular embodiment shown in FIG. 1, the first platform 14 a ofthe scaffold 14 supports a conventional coiled tubing injector 20. Shownwithin the body of the injector is the injector drive 36 to whichgripper blocks are attached (not shown). Disposed above the injector 20is a curved guide system known as a “gooseneck” 22. The function of thegooseneck 22 is to guide the coiled tubing CT into the injector 20 as itis being unwound from a coiled tubing reel 24. Another guide systemknown as the “horsehead” 34 is disposed above the coiled tubing reel 24to guide the coiled tubing CT emerging therefrom.

In certain embodiments, the coiled tubing CT has an outer diameter (OD)of 2.875 inches and the thickness of the wall of the coiled tubing CT is0.156 inches. These dimensions are compatible with the stresses imposedon the coiled tubing CT during the assembly process. It is advantageousto also provide a second scaffold platform 14 b to facilitate access byoperators to upper portions of the scaffold 14 which are describedbelow.

In FIG. 1, the facility 10 is shown in a state after the coiled tubingCT has been injected into the deviated well 12 to its specified depthfor assembly of a well heater to specified length. Furthermore, thecoiled tubing CT has been cut and it is seen that one end extends upwardfrom the wellhead 16 and the other remaining section of coiled tubing CThas been reeled back onto the coiled tubing reel 24 and now its cut endextends a short length outward from the horsehead 34. The downhole endof the coiled tubing CT is covered by a component known as a “bullnose”CT-B. The skilled person will recognize that a number of different coverdesigns may be used to cover the down-hole end of the coiled tubing andthat such alternatives are within the scope of the invention. Aconventional coiled tubing support means 26 such as a hand slip unit ora support ram (or both) is provided to hold the coiled tubing CT inplace at the well head 16. This support means 26 is needed to preventthe cut end of the coiled tubing CT from falling down into the deviatedassembly well 12 which may be significantly longer and deeper than thedefined length of the coiled tubing CT. Even in cases where the bullnoseCT-B reaches the bottom of the well, it is advantageous to employ asupport means 26 to suspend the coiled tubing CT in order to reducestresses on the coiled tubing CT and the cables C-1, C-2 and C-3contained therewithin.

Three heater cables C-1, C-2 and C-3 are shown extending fromcorresponding heater cable reels 28 a, 28 b and 28 c. In certainembodiments, these cables C-1, C-2 and C-3 are mineral insulated cableswhich will be described in more detail below, with reference to FIGS. 4Aand 4B. In certain embodiments, the cables C-1, C-2 and C-3 each have anouter diameter of 0.85 inches. The skilled person will appreciate thatwhile the example embodiments of the well heater described herein employthree cables, other arrangements are possible wherein one, two, or morethan three cables are used. The skilled person can select appropriatecoiled tubing sizes to accommodate different numbers of cables and adaptthe other components of the facility to be compatible with suchalternatives without undue experimentation.

Returning now to FIG. 1, as lengths of cables C-1, C-2 and C-3 areunwound from their respective cable reels, 28 a, 28 b and 28 c they passover respective cable sheaves 30 a, 30 b and 30 c which hang from asheave stand 32 connected to the scaffold 14 and forming an upper partthereof. The cables C-1, C-2 and C-3 then pass through the injector 20and are guided by a series of cable gripper blocks (integrated with theinjector) during the process of driving/injecting the cables C-1, C-2and C-3 into the coiled tubing CT. The cable gripper blocks aredifferent from conventional coiled tubing gripper blocks which have asingle larger indentation for holding a single length of coiled tubingCT in place. These cable gripper blocks are described in more detailhereinbelow. Conventional coiled tubing gripper blocks are used whencoiled tubing CT is injected into the deviated assembly well 12.

The cables C-1, C-2 and C-3 pass through the injector 20 and are routedinto the coiled tubing CT. The coiled tubing CT thus acts as aprotective cover for the cables C-1, C-2 and C-3 and forms an outersidewall along the length of of the well heater.

In order to monitor the temperature of the assembled well heater, it isnecessary to include at least one means of temperature measurement. Inthe example embodiment of FIG. 1, the facility 10 is provided with theability to assemble a well heater having a single means of temperaturemeasurement. However, in alternative embodiments, the facility may bemodified to include one or more additional means of temperaturemeasurement. This may be done by providing additional reels oftemperature lines and clamping these additional lines to the cables.Customized clamps for this purpose may be designed and constructed bythe skilled person without undue experimentation. The embodiment of thefacility shown in FIG. 1 produces a well heater with a fiber optic cableacting as the single temperature line T. This fiber optic cable can beused for distributed temperature sensing. The purpose of a distributedtemperature sensor is to record temperatures along the optical sensorline as a continuous profile and typically provides highly accuratetemperature readings over very long distances.

In some cases, it may be appropriate to include only one means oftemperature measurement, such as only a fiber optic line or only athermocouple line. Such embodiments are within the scope of theinvention.

In FIG. 1, it is seen that the temperature line T (illustrated with adot-dashed line) is withdrawn from its reel 38 and passed through asheave 40 prior to running it through the injector 20 alongside cableC-3. Advantageously, the temperature line T is clamped to one of thecables (not shown) at a plurality of vertical positions above thewellhead as the cables C-1, C-2 and C-3 are inserted into the coiledtubing CT. Advantageously, the length of the temperature line T isessentially the same as the length of the cables C-1, C-2 and C-3 inorder to provide distributed temperature sensing measurements along theentire length of the cables C-1, C-2 and C-3.

In alternative embodiments, at least a second means of temperaturemeasurement in the well heater is provided by a thermocouple line (notshown). In such embodiments, the facility is modified by adding anadditional thermocouple line reel and sheave to produce such a wellheater. The thermocouple sheave may also be supported by the sheavestand 32 in such alternative embodiments.

In alternative embodiments of the inventive facility, a conventionalcoiled tubing straightener of the type generally known in the art (notshown in FIG. 1) is provided above the injector 20 and connected to theinjector 20, the scaffold 14 or the sheave stand 32. It is advantageousto employ a coiled tubing straightener because the coiled tubing CTretains “shape memory” curvature from its significant time spentresiding on the coiled tubing reel 24. It is desirable to remove thiscurvature to give the coiled tubing CT a straight profile while it isbeing injected into the well 12.

In certain alternative embodiments of the inventive facility, inaddition to a conventional coiled tubing straightener, there is alsoprovided a cable straightener (not shown in FIG. 1) which operatesaccording to the same functional principles as the coiled tubingstraightener. The cables C-1, C-2 and C-3 also reside on theirrespective reels 28 a, 28 b and 28 c for extended periods and retainshape memory curvature which should be minimized or eliminated beforeinjection of the cables C-1, C-2 and C-3 into the well 12. The cablestraightener is connected to the injector 20, the scaffold 24 or thesheave stand 32.

In embodiments of the facility that employ both a coiled tubingstraightener and a cable straightener which reside above the injector,it is advantageous to provide a swivel means for one or the other.Advantageously, the coiled tubing straightener is disposed below thecable straightener and the cable straightener unit is provided with aswivel means that allows it to be moved away from the line of entry ofcoiled tubing CT into the injector 20 during the point in the assemblyprocess when coiled tubing CT is being injected. When it is time in theprocess for the cables C-1, C-2 and C-3 to be injected, the cablestraightener can then be replaced to its location above the injector 20to straighten the cables C-1, C-2 and C-3 prior to their entry into theinjector 20.

Another embodiment of the facility will now be described with referenceto FIG. 2 which shows a plan view of the facility that includes somefeatures which are not shown in FIG. 1. Likewise, certain features shownin FIG. 1 are omitted from FIG. 2 to preserve clarity. For ease ofrelating features of the facility embodiment of FIG. 2 to the featuresof the facility embodiment shown in FIG. 1, similar reference numeralsin the 100 series are used. In FIG. 2, reference numerals indicatingfeatures not shown in FIG. 1 are identified by odd numbers in the 100series.

In the plan view of FIG. 2, there is shown a facility 100 with ascaffold 114 disposed above the circumference of a wellhead 116. Thescaffold 114 has a first platform 114 a to allow access of operators tothe injector 120 and a second platform 114 b above the first platform114 a to allow access to other elevated components which will bedescribed below.

A coiled tubing straightener 123 (one of the optional features not shownin FIG. 1) is located above the injector 120 and may be supported by thebody of the injector 120, the scaffold 114 or the sheave stand 132. Inthis particular embodiment, a cable straightener 125 (another optionalfeature not shown in FIG. 1), is disposed above the coiled tubingstraightener 123. The cable straightener 125 is shown to the left of thecoiled tubing straightener 123 and connected by a swivel mechanism 127.The swivel mechanism 127 allows the cable straightener 125 to be moveddirectly over the injector 120 so that the cables C-1, C-2 and C-3 canbe straightened immediately before they enter the injector 120.

The cable reels 128 a, 128 b and 128 c are generally located centrallywithin the facility 100 and sufficiently close to their respective cablesheaves 130 a, 130 b and 130 c to keep an adequate degree of tension onthe cables C-1, C-2 and C-3. In some embodiments, the cable reels aredisposed in a semi-circle pattern generally centered on the location ofthe coiled tubing injector rather than a straight row as shown in FIGS.1 and 2.

This facility embodiment 100 includes means for installation of twotemperature lines in a well heater during assembly of the well heater.The first temperature line is a thermocouple line TH which extends fromthermocouple reel 138 a and over sheave 140 a prior to entry into theinjector 120. The second temperature line is a fiber optic line FO whichextends from fiber optic reel 138 b and over sheave 140 b alongside theinjector 120 and into the coiled tubing CT.

Also shown in FIG. 2 is the coiled tubing reel 124 to the left of thescaffold and coiled tubing CT extending therefrom and passing throughthe horsehead 134 before extending to the gooseneck 122. The skilledperson will appreciate that alternative embodiments will have the coiledtubing reel 124 to the right of the scaffold 114 and the temperatureline reels 138 a and 138 b disposed to the left of the scaffold.However, it is advantageous to have the cable reels 128 a, 128 b and 128c disposed generally parallel with the coiled tubing injector 120 or ina semi-circle arrangement generally centered on the coiled tubinginjector 120 although some angling of the cable reels 128 a, 128 b and128 c with respect to the longitudinal plane of the sheave stand 132 ispermissible and may be determined without undue experimentation.

The embodiment of the facility 100 shown in FIG. 2 includes a controlcenter 151 for computerized control and monitoring the rate ofdeployment of coiled tubing CT, cables C-1, C-2 and C-3 and temperaturelines TH and FO from their respective reels 138 a and 138 b and formonitoring the rate of injection of the same components into the well(as indicated generally by the dot-dashed lines extending from thecontrol center to the coiled tubing reel 124, injector 120, cable reels128 a, 128 b and 128 c and temperature line reels 138 a and 138 b. Incertain embodiments, the control center is elevated with a scaffold (notshown) to allow the operator to visualize most or all of the equipmentof the facility 100 while monitoring various parameters relating toassembly of the well heater on a computer monitor. In certainembodiments, the communication between the control center 151 and thevarious components described above is conducted wirelessly.

The embodiment of the facility 100 shown in FIG. 2 includes agantry-type crane to move assembled and spooled well heaters from thespooling location to a delivery vehicle or to essentially any otherlocation within the facility. The crane is also generally useful formoving any other heavy components within the facility 100. Thecomponents of the crane include the hoist 161 which moves acrosssubstantially the entire width of the facility along a bridge 163. Thebridge extends between a pair of runway beams 165 a and 165 b and canmove across substantially the entire length of the facility along therunway beams 165 a and 165 b. In this manner, heavy components may behoisted from essentially any location and transported to essentially anylocation within the area of the facility 100.

In facility embodiments which include a covering structure such as ashed or hangar, it is advantageous to provide an access opening in thestructure to allow access of large vehicles such as trucks or train carsinto the facility for convenient transfer of reels containing assembledwell heaters to the vehicles, as well as movement of heavy items todifferent locations within the facility.

Overview of Main Structural Features of the Cable Heater

In FIG. 3, there is shown a general schematic representation of anassembled well heater 200 according to one embodiment of the invention.For greater clarity, the components of well heater 200 are labelledusing reference numerals in the 200 series, except for the cables whichretain their designations C-1 C-2 and C-3, the temperature line, whichretains its designation T and the coiled tubing and bullnose whichretain their designations CT and CT-B, respectively (as introduced inFIG. 1). The well heater 200 includes an outer protective wall which isformed of coiled tubing CT. The “bullnose” CT-B is attached to thedown-hole end of the coiled tubing. Three mineral insulated cables C-1,C-2 and C-3 are contained within the coiled tubing CT. The cables C-1,C-2 and C-3 are of identical construction in this particular embodimentand will be described in more detail below.

The cables C-1, C-2 and C-3 are connected at the down-hole end by aconnection type known in the art as a “wye splice” 214. This wye splicearrangement 214 allows three-phase electrical power to be run throughthe cables C-1 C-2 and C-3, thereby generating heat through theelectrical resistance at the resistive section of each cable (asdescribed in detail below). Three-phase electrical power is a commonmethod of alternating-current electric power generation, transmission,and distribution. It is a type of polyphase system and is the mostcommon method used by electrical grids worldwide to transfer power. Itis also used to power large motors and other heavy loads. A three-phasesystem is usually more economical than an equivalent single-phase ortwo-phase system at the same voltage because it uses less conductormaterial to transmit electrical power. The following description assumesthe use of three-phase power, however, it is understood that other powerprofiles may be utilized. Other means for connecting the resistiveheating cables at the downhole end may be employed in alternativeembodiments.

In FIG. 3, it is seen that the wye splice 214 is protected by aninsulated wye splice cover 222. The wye splice cover 222 is providedwith a connector 224 which is used to connect the wye splice cover 222to a threading assembly (not shown) used during assembly of the heater.During assembly, at surface, the threading assembly allows the down-holeend of the wye-splice 214 to be threaded through the top of the coiledtubing injector. The injector provides the driving force for insertingthe cables C-1, C-2 and C-3 of the well heater into the well during theassembly process (described in detail below).

A generalized cable support assembly used for supporting the cablesduring assembly of the well heater 200 within the assembly well will nowbe briefly described. More specific embodiments of a cable supportassembly will be described hereinbelow. The main foundational componentof both the temporary and permanent cable support systems is a cablesupport adapter 218 which is permanently connected to the top of thecoiled tubing CT by welding or other connection means. In certainembodiments the cable support adapter provides two main functions; (i)it provides an extension of the coiled tubing with an inner sidewallsurface with sufficient tensile strength to support the weight of thecables by weight bearing frictional contact in a permanent cable supportsystem; and (ii) it provides a surface appropriate for temporaryvertical support of the weight of the cables by a cable bundle clamp.These two functions will be described in more detail hereinbelow.

Returning now to FIG. 3, it is seen that the cable support adapter 218fits over the coiled tubing CT and is attached thereto by welding orother equivalent permanent attachment means. The cable support adapter218 provides a customized termination of the upper end of the coiledtubing of the well heater 200 and has surfaces adapted for supporting acable support structure 220 which holds the cables C-1, C-2 and C-3 inplace against the inner sidewall of the cable support adapter 218 suchthat their combined weight is fully supported against the inner sidewallof the cable support adapter 218.

The top ends of the cables C-1, C-2 and C-3 are covered by insulatedcable inserts 216 a, 216 b and 216 c to prevent voltage leaks anddegradation of the insulating layer of the cables C-1 C-2 and C-3. Freeconducting cores of the cables extend from the tops of the inserts (notshown). With the installation of these insulated cable inserts 216 a,216 b and 216 c the cables are configured for connection to anelectrical source (not shown). An example embodiment of the insulatedcable inserts will be described in more detail hereinbelow in context ofFIGS. 24 and 25.

In FIG. 3, it is further seen that the well heater 200 is provided witha temperature measurement line T. The temperature measurement line T canbe a thermocouple line for making point temperature measurements or afiber optic line configured for distributed temperature sensing.Advantageously, the temperature measurement line T is clamped to thebundle of cables C-1, C-2 and C-3 at intervals sufficient to preventlooping or tangling of the temperature measurement line T. In certainembodiments, several thermocouple lines of varying lengths are used toprovide spot temperature measurements at several discrete locationsalong the length of the well heater 200. In certain embodiments, thewell heater 200 includes a fiber optic line and several thermocouplelines so that both distributed temperature measurements and several spotmeasurements can be made by the fiber optic line and the thermocouplelines, respectively. In the embodiment shown in FIG. 3, for the purposeof clarity, only one temperature measurement line T is shown and isclamped to cable C-3 by clamps 230 a and 230 b. A distance of about10-25 m typically provides appropriate spacing between clamps.

In FIG. 3, it is seen that the upper part of the assembled well heater200 is covered by a sleeve 226 which fits over the cable support adapter218. The top surface of the sleeve 226 is provided with a connector 234for connecting to a retrieval system (not shown) as well as forconnecting to a protective cover 232. The retrieval system allows thetop portion of the well heater 200 to be threaded upwards and throughthe injector which, when run in reversal mode with coiled tubing gripperblocks, provides the force required to withdraw the well heater from thewell for spooling onto a coiled tubing reel. The spooled well heater 200is then ready for transport to its location of deployment.

Advantageously in certain embodiments, the assembled well heater 200 isspooled on a coiled tubing reel which has a start hole (not shown) forinsertion of the up-hole end of the assembled heater, and a curved ramp(not shown) is connected to or integrally formed with the reel adjacentto the start hole on the emergent side of the start hole. The up-holeend of the assembled heater is pulled through the start hole and ridesup on the curved ramp. This action gradually curves and preventsdeformation of the portion of the assembled heater that is pulledthrough the start hole during the process of immobilizing the up-holeend of the well heater on the reel.

Resistive Heater Cables

In FIG. 4A there is shown a partially exploded perspective view of asingle resistive heater cable C. A cross section of a portion of thecable C taken in plane 4B is shown in FIG. 4B. In FIGS. 4A and 4B, itcan be seen that the cable C has a conducting core 302 formed of aconductor such as copper, for example. Other conductors may be used inalternative embodiments. The conducting core is surrounded by aninsulator layer 304 comprised of a mineral insulator (such as magnesiumoxide, for example). A sheath 306 formed of a relatively inertprotective material such as stainless steel is provided over theinsulator layer 304. The copper conducting core 304 is further definedby having at least one resistive core section 308 for generating heat atone portion of the cable C. If, for example, the conducting core 302 isformed of copper, a suitable material for the resistive core section 308is a copper-nickel alloy, such as copper-nickel alloy 180 whichfunctions as a resistive section. The skilled person will recognize thatif the conducting core 302 is formed of another conducting material inalternative embodiments, a different compatible alloy should be selectedto form the corresponding resistive section 308. The skilled person isto also understand that the length of the resistive section 308 isdesigned for placement at positions in the reservoir where heat isrequired.

The skilled person will recognize that the position of the resistivesection 308 along the length of an individual well heater will dependupon various parameters such as the depth and horizontal extension ofthe drilled heater well, for example. Modeling of reservoirs and heatersmay be performed to determine the optimal length of the resistivesection 308 as well as its location along the length of an individualcable C (however, the location of the resistive section should besubstantially identical for the three cables, for example, in theembodiment of the well heater shown in FIG. 3). In some embodiments, theresistive section 308 can be as long as about 2000 m. It is advantageousif the resistive section 308 does not extend into the wye splice becauseelectrical current should run efficiently through this component. Insome embodiments, a non-resistive section of about 5 to about 15 m inlength is provided adjacent to the wye splice. Similarly, at the upholeend of a TAGD well where heating is not required, a non-resistivesection corresponding to the vertical depth of the TAGD well (i.e. priorto the beginning of the deviated or horizontal portion of the well) maybe provided.

Wye Splice

The structure of one particular embodiment of the wye splice (indicatedin FIG. 3 by reference numeral 214) is shown in more detail in FIGS. 5Ato 5D. This particular embodiment of the wye splice uses referencenumerals in the 400 series along with the specific reference numeralsreferring to the specific cable components in FIGS. 4A and 4B in the 300series. In the detail views shown in FIGS. 5A and 5B, of it is seen thatthe wye splice 400 serves to conductively connect each of the threecables C-1, C-2 and C-3. It is also seen that the ends of the cables arestripped down to their respective conducting cores 302 a, 302 b and 302c and connected to an end plate 402 (which is shown by itself inperspective view in FIG. 5D). The conducting cores 302 a, 302 b and 302c extend through respective openings 410 a, 410 b and 410 c in the endplate 402 such that the sheath layers of the cables C-1, C-2 and C-3make contact with the cable entry side of the end plate 402 (FIG. 5A).Advantageously, the end plate 402 is also formed or at least coveredwith an inert protective material which is the same as, or compatiblewith, the material used to cover or form the cable sheath (such asstainless steel), thereby allowing each of the cable sheaths to bewelded to the contact surface of the end plate 402.

Another component herein designated the wye splice connector 404 (shownalone in perspective view in FIG. 5C) is then attached to the ends ofthe conducting cores 302 a, 302 b and 302 c. In this particularembodiment, the wye splice connector 404 is in the shape of a disk withcircular slots 412 a, 412 b and 412 c to hold the conducting cores 302a, 302 b and 302 c in place during the process of attachment.Advantageously, the wye splice connector 404 is formed of the sameconducting material as the conducting cores 302 a, 302 b and 302 c, tofacilitate attachment by welding for example. The wye splice connectordisk 404 allows the three phase electrical current to be conductedthrough each of the three cables C-1, C-2 and C-3.

At this stage of the assembly process, the conducting cores 302 a, 302 band 302 c and wye splice connector disk 404 are exposed and in need ofinsulation to prevent electrical discharge. Advantageously, all surfacesof the exposed conducting cores 302 a, 302 b and 302 c and the wyesplice connector 404 are rounded and smooth to prevent such electricaldischarges, which may be caused by surface irregularities. A wye splicecover 406 (shown in FIGS. 5A and 5B) in the form of a tubular sleeveclosed at one end is fitted over the wye splice 400. The wye splicecover 406 makes contact at its open end with the surface of the endplate 404 from which the conducting cores 302 a, 302 b and 302 c extend.Advantageously in this particular embodiment, the wye splice cover 406also is formed of, or at least plated with, stainless steel so that itcan be effectively welded to the stainless steel contact surface of theend place 402. The wye splice cover 406 has an opening 408 which isprovided as a means for adding an insulating powder such as magnesiumoxide to the space inside the wye splice cover. Thus, after attachmentof the wye splice cover 406, insulating powder such as magnesium oxideis introduced through opening 408 to fully fill the cavity therein andprovide insulation around each of the exposed conducting cores. Opening408 is then sealed.

Overview of an Embodiment of a General Process for Assembly of WellHeaters

In furtherance of the general assembly description provided above, thissection provides a brief overview of one example of assembly of a wellheater which includes the components described hereinabove. Variationsin the order of assembly are possible in alternative embodiments andthese variations will be discussed in context of this exampleembodiment. The description of the components of the well heater refersto the components and reference numerals of FIG. 3.

In certain embodiments, the process of assembly may take place at a wellheater facility such as, for example the facility described in FIG. 1 orFIG. 2. The equipment and features of the facility will be discussed indetail below.

In certain embodiments, the well heater 200 is assembled at a site thatincludes a pre-drilled assembly well which may be either a vertical wellor a deviated well which deviates from vertical by about 30 degrees toabout 50 degrees from the vertical. In other embodiments, the deviatedwell deviates from vertical by about 35 to about 45 degrees from thevertical. Various embodiments of the assembly well will include acombination of both vertical and deviated sections. The respectivelengths of each section and the degree of deviation are generallydesigned such that the weights of the well heater components are atleast partially supported by the sloping sides of the deviated sectionwhile enabling all components to be easily run into the well.

In the first step of this example process, which refers to componentparts of the embodiment of the well heater illustrated in FIG. 3, a reelof conventional coiled tubing CT is provided and unspooled from the reelas needed. The coiled tubing CT is metal piping, which may range indiameter from 1 inch to 3.5 inches. In general, coiled tubing istypically used for interventions in oil and gas wells and sometimes asproduction tubing in depleted gas wells. In certain embodiments of thepresent process for assembling well heaters, the outer diameter (OD) ofthe coiled tubing is 2.875 inches.

The bullnose cover CT-B is connected to the free end of the coiledtubing CT. Welding is a convenient means of making such a connection.

After installation of the bullnose CT-B, the coiled tubing CT isinjected into the well using a conventional coiled tubing injector. Theinjector is configured with gripper blocks that fit the size of coiledtubing being used. The length of coiled tubing CT injected will dependupon the total length of well heater 200 being constructed.

When the coiled tubing CT has been injected to its specified depth inthe well, it is supported above the wellhead according to known methodsusing conventional coiled tubing slips and/or conventional support ramsor both, and then cut from the coiled tubing reel, thereby forming afree open end. The cable support adapter 218 is then connected to theopen top of the coiled tubing CT. The purpose of the cable supportadapter 218 is to provide the foundation for the cable support structure220 which holds the weight of the three resistive cables C-1, C-2 andC-3.

The coiled tubing CT and cable support adapter 218 are now ready forinsertion of the cables C-1, C-2 and C-3. The cables C-1, C-2 and C-3are provided on individual cable reels (See FIGS. 1 and 2). Afterunspooling of the cables C-1, C-2 and C-3 through the coiled tubinginjector to a length sufficient to allow manual manipulation at anappropriate location in the facility, the wye splice 214 is constructedby welding the connector parts to ensure electrical conduction among thethree cables C-1, C-2 and C-3. When the welding is complete, the wyesplice 214 is provided with a cover 222 which may also be welded inplace. As described above, in certain embodiments, the cover includes anopening (opening 408 shown in FIG. 5A), into which a powder-basedinsulator such as magnesium oxide can be added to prevent voltage leaksfrom the wye splice 214. The opening may be then sealed and welded inplace. The wye splice cover contains a connector 224 for connecting aknuckle joint (not shown) which facilitates the threading of the wyesplice cover 222 and the connected cables C-1, C-2 and C-3 through theinjector for injection into the coiled tubing CT in the assembly well.In certain embodiments of this general process, the interior of the wyesplice cover 222 is vacuum dried prior to sealing the opening 408.

Within the injector, the three cables C-1, C-2 and C-3 are placed withina set of cable gripper blocks for holding the three cables C-1, C-2 andC-3 in place for simultaneous injection into the coiled tubing. Thecustom-designed gripper blocks each have three indentations for holdingthree cables C-1, C-2 and C-3. Otherwise, the gripper block connectormembers are essentially identical to the analogous connector membersused in the conventional coiled tubing gripper blocks and areconveniently interchangeable with the coiled tubing gripper blocks. Anembodiment of cable gripper blocks will be described in more detailhereinbelow in context of FIGS. 27-29.

Returning now to FIG. 3, traveling along with the three cables C-1, C-2and C-3 into the coiled tubing 210 is at least one temperaturemeasurement line T which may be a thermocouple line or a fiber opticline. A thermocouple line is used for point temperature measurements anda fiber optic line is used for distributed temperature measurements. Incertain embodiments, the well heater 200 includes both a thermocoupleline and a fiber optic line in order to provide redundancy in the eventof failure of one of the temperature measurement lines. In certainembodiments, the temperature measurement line T is clamped to one of thecables. Individual clamps such as clamps 230 a and 230 b may be providedat intervals ranging from about 10 m to about 25 m in order to preventlooping and tangling of the line as it travels along with the cablesC-1, C-2 and C-3 into the coiled tubing CT.

After the three cables C-1, C-2 and C-3 have been injected to thespecified depth within the coiled tubing CT, they are initiallysupported above the well head by the combination of the injector and theheater cable reels. In order to effectively transfer the weight of thecables to the coiled tubing to enable the heater cables to be cut, afirst temporary support clamping assembly is connected to the cablesC-1, C-2 and C-3, followed by connection of a second support clampingassembly which is movable and carries the permanent support componentswhich are installed to form the permanent cable support structure 220.Embodiments of the temporary cable support systems and permanent cablesupport structure 220 will be described in detail hereinbelow in contextof FIGS. 6-20.

Returning now to FIG. 3, after the permanent support structure 220 is inplace, the exposed up-hole ends of the cables C-1, C-2 and C-3 areprotected by a cover 232. Optionally in certain embodiments, a sleeve226 may be connected to the adapter 218 prior to connection of the cover232. The cover may be provided with a connector 234 for connection oftools used to withdraw the assembled well heater 200 from the well.

Overview of Cable Support Systems

All embodiments of the well heater assembly process include the step ofinjecting resistive heater cable(s) into coiled tubing in a vertical ordeviated well. This process step provides various advantages relating tospace requirements, efficiency and quality control as previouslydescribed, but also introduces new problems, such as a requirement forsupport of the cables as they hang within the coiled tubing in the wellat the point in the assembly process before they are cut from theirrespective source cable reels. There is also a need to provide moveablesupport to the cables to enable an operator to lift, lower and fix thetops of the cables into place at the top of the coiled tubing. The cablesupport systems described hereinbelow have been developed to addressthese needs.

As noted above, the cable support system includes a “cable supportadapter” which is exemplified by component 218 in FIG. 3. The purpose ofthe cable support adapter 218 is to modify the end of the coiled tubingso that it is capable of supporting the weight of the cables C-1, C-2and C-3 before they are cut from their respective cable reels. Thesupport provided by the cable support adapter 218 allows the cut ends ofthe cables C-1, C-2 and C-3 to be held in place and processed. Aftersuch processing, the cables C-1, C-2 and C-3 are then supportedpermanently by a support structure 220 which provides engagement to aninner portion of the cable support adapter. In fulfilling this function,certain embodiments of the cable support adapter 218 and supportstructure 220 provide an inner surface with sufficient tensile strengthto allow the cables C-1, C-2 and C-3 to be wedged in a manner whichprovides support of the entire cumulative weight of the cables withinthe coiled tubing CT. Another function provided by the cable supportadapter 218 is to provide a foundation for assembly of a laterallyextended platform surface for supporting a cable bundle clamp. Theskilled person will appreciate that a number of structural variations ofcable support adapters 218 are possible which would fulfill theabovementioned functions. Example embodiments will be describedhereinbelow.

In general terms, the second cable support system (not shown in FIG. 3)provides moveable support to the cables. It is is used to carry andlodge the permanent support structure 220 within the interior of thecable support adapter 218. Embodiments of the second cable supportsystem and the permanent support structure are described in more detailhereinbelow with reference to FIGS. 11-20. Features provided by thissecondary support structure include the provision of a foundationagainst the upper portion of the cables which allows for connection of alifting means and also the provision of a foundation for connection ofthe permanent support structure.

Cable Support Adapter

As noted in general terms hereinabove, the cable support adapterprovides the primary function of adapting the coiled tubing forsupporting the cables in a temporary aspect and as a permanent feature.An important function of the cable support adapter is to provide aninner surface with sufficient tensile strength to support the weight ofthe cables by weight bearing frictional contact in a permanent cablesupport system. This is necessary because the inner surface of coiledtubing may not meet this requirement. Another feature of certainembodiments of the cable support adapter is to provide a temporarysubstantially flat and laterally extended platform surface to support atemporary cable bundle clamp which supports the cables temporarily whilethe cables are cut and processed prior to construction of the permanentsupport structure. This is needed because the upper rim of the coiledtubing is not expected to be strong enough to support the lower surfaceof a cable bundle clamp. When the cable bundle clamp is engaged to thebundle of cables, it is lowered along with the cables until its bottomsurface rests upon the flat platform surface of the cable supportadapter. This arrangement provides temporary cable support which enablesthe weight of the cables to be slacked off from the cable reels,allowing the cables to be cut therefrom.

A number of possible structural arrangements may be developed to fulfillthese two main functions of providing an appropriate inner surface and aflat laterally extended platform surface for supporting a cable bundleclamp. In one embodiment shown in FIGS. 6A and 6B, there is provided aone-piece cable support adapter in the form of an open ended block whichis connectable to the coiled tubing by welding or other means and has aninner surface with sufficient tensile strength to support the weight ofthe cables by weight-bearing frictional contact. This embodiment of thecable support adapter has an upper flat platform surface which is widerthan the outer diameter of the coiled tubing. An example of such anembodiment of the cable support adapter is shown in FIG. 6. FIG. 6Ashows a perspective view of the block-shaped cable support adapter 501by itself and FIG. 6B shows a perspective view of the cable supportadapter 501 attached to coiled tubing CT and with a cable bundle clamp511 attached to the cables C-1, C-2 and C-3. It is seen in FIGS. 6A and6B that the cable support adapter is a simple block with a cylindricalopening. It is possible to substitute a cylindrical shaped cable supportadapter (not shown) for the block shaped cable support adapter, as longas the platform surface area is sufficient to support the cable bundleclamp. The inner sidewall 503 of the opening has sufficient tensilestrength to support the weight of the cables by weight bearingfrictional contact. The cable support adapter has an upper platformsurface 505 which is wider than the outer diameter of the coiled tubingCT. This platform surface 505 provides support for the cable bundleclamp 511.

Another cable support adapter embodiment which is shown in FIGS. 7A to7C with reference numbers in the 600 series. This cable support adaptersystem is constructed of a permanent component and two temporarycomponents. Collectively, in this example, the three components, whenassembled, are referred to as a cable support adapter. After thetemporary components are removed, the remaining permanent component(receptacle 600) is also referred to as the cable support adapter. Themain features of the cable support adapter 218 of FIG. 3 are generallysimilar to the main features of the receptacle 600 of FIG. 7A althoughadditional features of the receptacle 600 are described in context ofFIG. 7A. In this particular embodiment, the receptacle 600 provides aninner sidewall 602 with sufficient tensile strength to support theweight of the cables by weight-bearing frictional contact. The twotemporary components are associated with the permanent component for thepurpose of providing an upper laterally extended platform surface tosupport a cable bundle clamp (to be described with reference to FIG. 8).At the point in the well heater construction process when the upperplatform surface and cable bundle clamp are no longer needed, the twotemporary components are removed and the permanent component (in thepresent case the receptacle 600) remains in place. This is in contrastto the embodiment of FIG. 6 where the platform surface 505 provided bythe block-shaped cable support adapter 501 remains permanently engagedto the coiled tubing CT.

Returning now to FIG. 7A, the permanent component is a cylindricalreceptacle 600 which is configured for permanent attachment to the cutend of the coiled tubing by welding or other means. The receptacle 600has an inner sidewall 602 with sufficient tensile strength to supportthe weight of the cables by weight bearing frictional contact whencombined with additional permanent support components (which areprovided by various embodiments of “wedging tube” embodiments which willbe described in detail hereinbelow with reference to FIGS. 11-15). Inthis particular embodiment of the cable support adapter component shownin FIG. 7A, the receptacle 600 is provided with two sets of threads 604and 606 on the upper portion of the outer sidewall of the receptacle600. These threads 604 and 606 are used for connection of othercylindrical components which will be described in detail hereinbelow.The receptacle 600 is also provided with a circumferential groove 608which in this particular embodiment, is approximately centered withrespect to the length of the receptacle 600. The purpose of thecircumferential groove 608 is to provide an engagement surface for oneof the two temporary components of the cable support adapter which willbe described in detail hereinbelow. The lower portion of the receptacle600 terminates in a reduced diameter portion 610 which is inserted intothe cut end of the coiled tubing, thereby providing a means ofengagement of the receptacle to the coiled tubing. This means ofengagement facilitates the process of permanently attaching thereceptacle 600 to the coiled tubing, for example by welding.

Turning now to FIG. 7B, there is shown an exploded view of a firsttemporary component of the cable support adapter which is referred toherein as the lateral extension clamp 620. The purpose of this componentis to provide a foundational flat surface which is laterally extendedfrom the outer diameter of the receptacle 600. The lateral extensionclamp 620 is formed of two C-shaped halves 622 a and 622 b of a mainbody which are connected together by a pin and washer set arrangement onthe left side of the main body halves 622 a and 622 b and a bolt andwasher arrangement on the right side of the main body halves 622 a and622 b. The halves 622 a and 622 b of the lateral extension clamp 620have inner surfaces radiused to match the outer diameter of thereceptacle 600. These inner surfaces are each provided with ridges 624 aand 624 b which are matched to the circumferential groove 608 of thereceptacle 600. When the lateral extension clamp 620 is clamped to theouter sidewall of the receptacle 600 (as shown in the exploded view ofFIG. 9), the ridges 624 a and 624 b reside within the groove 608 andthus the lateral extension clamp 620 is provided with additionalclamping support. As noted above, the lateral extension clamp 620provides a foundational flat surface laterally extended from the outerdiameter of the receptacle 600. This flat surface is constructed fromthe combination of surfaces 626 a and 626 b of the halves 622 a and 622b of the lateral extension clamp 620 when it is clamped on thereceptacle 600. Surfaces 626 a and 626 b combine to form a single flatsurface to support the extension platform 640 (the second temporarycomponent of the cable support adapter) whose features are highlightedin FIG. 7C. The arrangement of assembled components of the cable supportadapter will be shown in more detail in FIGS. 8 and 9 which aredescribed in detail hereinbelow.

Referring now to FIG. 7C, there is shown a second temporary component ofthe cable support adapter. This component is a C-shaped extensionplatform 640 whose purpose is to provide a platform surface 646 raisedabove the upper end of the receptacle 600 when the extension platform isin place resting upon the surfaces 626 a and 626 b of the lateralextension clamp 620. The extension platform 640 has a C-shaped base 642,a C-shaped support wall 644 and an upper C-shaped platform surface 646which together define a slot 643. When the extension platform 640 isused as a temporary component of the cable support adapter, the cablesreside within and extend upward from the slot 643 and the cable bundleclamp (described below) is placed on the platform surface 646. Forconvenience in transport of the extension platform, carrying handles 648a and 648 b are attached to the cylindrical portion 644 of the extensionplatform 640. These handles 648 a and 648 b facilitate manualmanipulation of the positioning of the extension platform 644,particularly at the point in the assembly process when the extensionplatform 644 is placed to position the exposed upper portions of thecables within the slot 643.

An embodiment of a cable bundle clamp appropriate for use with the cablesupport adapter embodiment of FIGS. 7A to 7C is shown in FIGS. 8A to 8C.FIG. 8A is a perspective view of the cable bundle clamp 650 in theassembled arrangement for storage (in the absence of the cable bundleitself) which includes a carrying bolt 651 to facilitate transport ofthe cable bundle clamp 650. It is to be understood that carrying bolt651 is removed from the cable bundle clamp 650 when it is clamped to abundle of cables (as will be seen in FIGS. 10 and 19, discussedhereinbelow). FIG. 8B is a top view of the cable bundle clamp in theassembled arrangement 650 after removal of the carrying bolt 651. FIG.8C is a perspective view of a central gripping member 656 of the cablebundle clamp 650. It is seen in FIGS. 8A and 8B that this embodiment ofthe cable bundle clamp 650 is formed from two clamp blocks 652 a and 652b with side plates 654 a and 654 b attached thereto by a set of boltswhich extend completely through the clamp blocks 652 a and 652 b and theside plates 654 a and 654 b. The clamp blocks 652 a and 652 b areprovided with inner surfaces which are shaped to conform to the outerwalls of the cable bundle which is, for the purposes of the presentembodiment, provided generally in a triangular shape. This embodiment ofthe cable bundle clamp also includes a central gripping member 656 (FIG.8C) which is placed in the center of the cable bundle and cooperateswith the clamp blocks 652 a and 652 b to grip the cable bundle in aconsistent configuration along the entire length of the cable bundleclamp 650, thereby preventing deformation and/or damage to the cables.The central gripping member 656 is provided with three radiused outersurfaces which are shaped to conform to the outer walls of the cables.Similar gripping threads may also be provided on the cable-contactingsurfaces of the clamp blocks 652 a and 652 b (not shown).

It is seen in the top view of the cable bundle clamp 650 of FIG. 8B thatthe clamp blocks 652 a and 652 b have interior surfaces shaped toconform to the outer walls of the cable bundle, which in this particularembodiment, is arranged in a triangular pattern. Other geometricarrangements are possible in alternative embodiments which may employmore or fewer cables. Clamp block 652 a has a single large radiusedsurface portion 653 a configured to accommodate a single cable (incooperation with the central gripping member 656) and clamp block 252 bhas two large radiused surface portions 653 b and 653 c, each configuredto accommodate an additional cable (in cooperation with the centralgripping member 656). In addition, the inner surface of clamp block 652a has two additional smaller radiused portions, 655 a and 655 b eachprovided to allow passage of a temperature line (not shown) through thecable bundle clamp 650. As the temperature lines are supported byclamping to the cables, it is not necessary for the cable bundle to gripthem and the smaller radiused portions 655 a and 655 b therefore providepassageways for the temperature lines without gripping.

For greater clarity, the assembly of the cable support adapter and thecable bundle clamp is now described with reference to the explodedperspective view of FIG. 9 and the side elevation view of FIG. 10. Thereduced diameter portion 610 of the receptacle 600 is placed inside theupper end of the coiled tubing and then the receptacle 600 is welded tothe coiled tubing CT. The cables C-1, C-2 and C-3 are injected into thecoiled tubing CT. The lateral extension clamp 620 is assembled with theridges 624 a and 624 b of the halves 622 a and 622 b of the lateralextension clamp placed in the groove 608 of the receptacle 600. When thelateral extension clamp 620 is assembled and bolted onto the receptacle600, surfaces 626 a and 626 b form a single upper surface. The extensionplatform 640 is then added to the assembly by placing its base 642 onthe upper surface of the lateral extension clamp 620 with the receptacle600 and cables C-1, C-2 and C-3 residing in the slot 643 of theextension platform 640. At this stage, the construction of the cablesupport adapter is complete. The cable support adapter includes thereceptacle 600 as a permanent component and the lateral extension clamp620 and extension platform 640 as temporary components. The completionof the cable support adapter with the temporary components installedallows the cable bundle clamp 650 to be installed and supported. This isdone by placing the central gripping member 656 in the middle of thecable bundle which is comprised of cables C-1, C-2 and C-3 and then theclamp blocks 652 a and 652 b and respective side plates 654 a and 654 bare bolted together with the series of bolts. When the cable bundleclamp 650 is securely fastened to the cables C-1, C-2 and C-3, they arethen lowered further into the coiled tubing until the bottom surfaces ofthe clamp blocks 652 a and 652 b rest upon the platform surface 646 ofthe extension platform 640. The lowering action may be provided by theaction of the coiled tubing injector (such as injector 20 of facility 10(FIG. 1) or such as injector 120 of facility 100 (FIG. 2), for example.Importantly, at this stage, there is enough room between the down-holeends of the cables (wye splice) and the sealed bottom of the coiledtubing CT to accommodate this downward movement of the cables. Once thecable bundle clamp 650 rests upon the platform surface 646, the weightof the cables C-1, C-2 and C-3 can be transferred from the cable reelsto the cable bundle clamp 650 and cable support adapter. Providing slackto the cables above the cable bundle clamp 650 transfers the weight ofthe cables C-1, C-2 and C-3 to the cable bundle clamp 650 and the cablesupport adapter, thereby allowing the cables C-1, C-2 and C-3 to be cutand processed.

The embodiment of the cable support adapter described with reference toFIGS. 7-10 (which includes a single permanent component and twotemporary components) has certain advantages over the single piece cablesupport adapter embodiment of FIG. 6. Most notably, the cable supportadapter embodiment of FIGS. 7-10 retains a narrow cylindrical profilewhich allows the assembled cable heater to be withdrawn from the wellusing the coiled tubing injector after the temporary lateral extensionclamp and extension platform are removed. The embodiment of FIG. 6 wouldlikely encounter problems in such a process its upper block profile,would likely not likely fit through the injection mechanism of mostconventional coiled tubing injectors. However, the embodiment of FIG. 6would otherwise be useful if some alternative means was employed towithdraw the assembled cable heater from the well.

Materials from which any or all of the embodiments of the components ofthe cable support adapter may be formed include steel and other similaralloys with and without coatings, which may be selected by the skilledperson without undue experimentation.

Permanent Cable Support System

With the provision of the cable support adapter and cable bundle clampdescribed above, the cables can be cut from their respective reels. Theresulting structure can be seen in the side elevation view of FIG. 10,wherein the coiled tubing containing the cables is now modified in orderto construct a permanent cable support system. The permanent cablesupport system is based upon the principle of adding a wedging member inthe shape of a tube (each embodiment of the wedging member describedbelow is hereinafter referred to as a “wedging tube”) to the spacebetween the inner side wall of the cable support adapter and the outersidewalls of the cables such that the inner shaped surfaces of thewedging tube grip the cables and the outer curved sidewall of thewedging tube frictionally engages the inner side wall of thereceptacle/cable support adapter. Such a process would be relativelysimple to perform manually if the cables were relatively short andlight. In such a simple case, the wedging tube could be inserted overcables, thereby allowing the cables to be gripped and lowered until thewedging tube becomes engaged against the cables and the inner side wallof the cable support adapter. However, certain embodiments of the wellheater described herein have cables which are thousands of meters long.In such cases, the collective weight of the cables is too heavy topermit manual manipulation and a mechanical power lifter is needed toraise and lower the cable bundle during the process of engaging thewedging tube with the inner side wall of the cable support adapter.

To address this problem, an assembly referred to herein as the “wedgingtube carrier” has been designed. The wedging tube carrier is attached tothe cable bundle and provides two main functions; (i) it serves to holdthe wedging tube during the process of inserting it into the cablesupport adapter and (ii) it provides a foundation for a liftingattachment to allow connection to a mechanical power lifter for raisingand lowering the wedging tube carrier and the cables so that the wedgingtube can be placed into the cable support adapter for permanent supportof the cables by the combination of the cable support adapter and thewedging tube.

The features of a number of example embodiments of wedging tubes willnow be described with reference to FIGS. 11-15 wherein the componentsassociated therewith are assigned reference numerals in the 700 series.

In FIGS. 11A and 11B, there are shown opposing perspective views of afirst embodiment of a wedging tube 705 which is of generally tubularconstruction with an end plate 707 (shown in detail on the right end ofthe perspective view of FIG. 11A which indicates the “up-hole” end ofthe wedging tube 705) defined by three large openings 709 a, 709 b and709 c, each provided to allow passage of a single cable of a bundle ofthree cables (not shown in FIGS. 11A and 11B). The outer diameter of theend plate 707 is greater than the diameter of the outer sidewall 713 ofthe wedging tube 705 and as a result, the end plate 707 is defined by anouter lip 708 whose function will be discussed in detail hereinbelow,with respect to the operation of the wedging tube carrier (shown inFIGS. 17 and 18). The openings 709 a 709 b and 709 c have identicaldiameters which are slightly greater than the outer diameter of each ofthe identical cables. The end plate 707 also has two additional openings711 a, 711 b for passage of temperature lines such as the previouslydiscussed thermocouple and/or fiber optic lines. The diameter of each ofthe openings 709 a 709 b and 709 c and the diameters of the smalleropenings 711 a and 711 b are maintained in the interior of the wedgingtube 705 as shown more clearly at the right end of the view shown inFIG. 11B which indicates the “down-hole” end of the wedging tube 705. Asa result, the wedging tube 705 has an interior structure defined bythree large circular sidewalls and two smaller circular sidewalls whichallow passage of cables and temperature lines, respectively. For thesake of clarity and although the interior structure of the wedging tube705 is interrupted by the presence of longitudinal slot openings asdescribed hereinbelow, the entire interior surface of the wedging tube705 is referred to as interior sidewall 718.

Wedging tube 705 has an outer sidewall 713 defined by four equi-spacedlongitudinal slots 715 a, 715 b, 715 c and 715 d which are open at thedown-hole end and which terminate in semi-circular ends near the endplate 707. These slots extend through the tube body to the innercircular sidewall 718. The purpose of the longitudinal slots 715 a, 715b, 715 c and 715 d is to confer compressibility to the main body of thewedging tube 705. This compressibility allows the wedging tube 705 to beplaced inside the cable support adapter (e.g. receptacle 600 of FIG. 7A)such that its outer sidewall 713 compresses against the inner sidewall602 of the receptacle 600 and its discontinuous curved inner sidewall718 compresses against the bundle of cables, thereby providing grippingaction to the outer sidewalls of each of the cables. This action wedgesand supports the entire weight of the cables inside the receptacle 600as they hang within the coiled tubing in the assembly well. The skilledperson will recognize that any significant variation in the lengths andwidths of the slots 715 a, 715 b, 715 c and 715 d will have an effect onthe compressibility of the sidewall of the wedging tube 705. Forexample, wider and/or longer slots will generally increase thecompressibility of the wedging tube 705 and narrower and/or shorterslots will generally decrease the compressibility of the wedging tube705. In addition, variations of the features of the shaped innersidewall 718 which will be described with respect to alternativeembodiments, also will vary the compressibility. These parameters may bevaried in various embodiments of the invention to provide a more rigidor more compressible wedging tube as needed in various embodiments ofwell heaters constructed using the methods described herein.

Shown in FIGS. 12A and 12B is another embodiment of the wedging tube 725in opposing perspective views similar to the views shown in FIGS. 11Aand 11B. This embodiment has a number of features similar to those ofthe wedging tube embodiment 705 of FIGS. 11A and 11B, including asimilar end plate 727, end plate lip 728, openings for cables 729 a, 729b and 729 c, openings for temperature lines 731 a and 731 b and outersidewall 733. One difference however is that three transverse slots 735a, 735 b and 735 c are provided in the body of this wedging tube 725 incontrast to the four longitudinal slots 715 a, 715 b, 715 c and 715 d ofthe wedging tube embodiment 705 of FIGS. 11A and 11B. The equi-spacedtransverse slots 735 a, 735 b and 735 c slice across the cylindricalsolid tube body and define a triangular inner solid body portion 739which occupies the majority of the inner volume of the wedging tube 725.The inner sidewall 738 of wedging tube 725 is therefore different fromthe inner sidewall 718 of wedging tube 705 of FIG. 11B. The skilledperson will recognize that a comparison of FIG. 11B with FIG. 12Bindicates that the solid wedging tube body of wedging tube 725 occupiesmore volume than that of wedging tube 705 and thus is less compressiblethan the tube body of wedging tube 705.

A variation of the wedging tube embodiment of FIGS. 12A and 12B is shownin FIGS. 13A, 13B and 13C. FIG. 13A is a perspective view of a wedgingtube 745 with detail of its down-hole end shown. FIG. 13B is a directview of the down-hole end of the same wedging tube 745. FIG. 13C is anexpanded view of the upper circle shown in FIG. 13B. This wedging tube745 has a number of features similar to those of the previousembodiments including an end plate 747 with an extending lip 748, anouter sidewall 753, openings 749 a, 749 b and 749 c for cables, andopenings 751 a and 751 b for temperature lines. A major differencehowever, is the presence of two parallel sets of three transverse slots755 a, 755 b, 755 c, 755 d, 755 e, and 755 f. The effect of these extraslots is to reduce the solid volume of the interior of the tube(relative to that of wedging tube 725). The inner triangle of this solidvolume which is formed by slots 755 b, 755 c and 755 e (see FIG. 13B) isless than that of wedging tube 725. Thus, the wedging tube 745 of thepresent embodiment is more compressible than that of wedging tube 725.The triangle tips 759 a, 759 b and 759 c of the solid interior volumereach the circumference of the outer sidewall 753 in contrast to thenext embodiment described hereinbelow.

A variation of the wedging tube embodiment of FIGS. 13A-13C is shown inFIGS. 14A-140. FIG. 14A is a perspective view of a wedging tube 765 withdetail of its down-hole end shown in a manner similar to FIG. 13A. FIG.14B is a direct view of the down-hole end of the same wedging tube 765.FIG. 14C is an expanded view of the upper circle shown in FIG. 14B. Mostof the features of wedging tube 765 are similar to those of thepreviously described wedging tube embodiment 745. Wedging tube 765 hasan end plate 767 with an extending lip 768, an outer sidewall 773,openings 769 a, 769 b and 769 c for cables, and openings 771 a and 771 bfor temperature lines. Wedging tube 765 also has two parallel sets ofthree transverse slots 775 a, 775 b, 775 c, 775 d, 775 e, and 775 f toreduce the solid volume of the interior of the tube. The inner triangleof this solid volume which is formed by slots 775 b, 775 c and 775 e(see FIG. 14B) is similar to that of wedging tube 745 with the exceptionthat the triangle tips 779 a, 779 b and 779 c are recessed and do notextend to the circumference of the outer sidewall 773. This has theeffect of making wedging tube 765 of the present embodiment morecompressible than wedging tube 745.

Another wedging tube embodiment is shown in FIGS. 15A and 15B. It isseen that this particular wedging tube embodiment is formed from threeseparate wedging tube segments 785 a, 785 b and 785 c. It is illustratedin FIG. 15A that each of the segments 785 a, 785 b and 785 c includes acorresponding end plate portion 787 a, 787 b and 787 c, end plate lipportion 788 a, 788 b and 788 c, outer sidewall 793 a, 793 b and 793 cand scalloped inner sidewall 798 a, 798 b and 798 c. When the threewedging tube segments 785 a, 785 b and 785 c are assembled as shown inFIG. 15B, the scalloped inner sidewalls 798 a, 798 b and 798 c cooperateto form the cable openings 789 a, 789 b and 798 c. The openings for thetemperature lines 791 a and 791 b are located in segments 785 a and 785b, respectively. The skilled person will recognize that this wedgingtube embodiment, being formed of three separate parts which may movewith respect to each other while the wedging tube is being manipulated,has the effect of reducing the overall rigidity of the tube.

The skilled person will appreciate that while each of the wedging tubeembodiments described hereinabove includes a provision for twotemperature lines, alternative wedging tube embodiments may include onlyone temperature line opening or more than two temperature line openings.Such alternatives are within the scope of the invention. In addition,the various features of the five wedging tube embodiments describedhereinabove may be provided in various combinations to produceadditional wedging tube embodiments. Appropriate alternative embodimentsmay be selected by the skilled person and are also within the scope ofthe invention.

FIG. 16 illustrates a partially exploded perspective view of some of theimportant features of the permanent components of one embodiment of thecable support adapter, including the receptacle 600, wedging tube 705,cables C-1, C-2 and C-3 and temperature lines TH and FO. The skilledperson will recognize that the alternative wedging tube embodimentsdescribed hereinabove will operate in a similar manner in fulfilling thefunction of supporting the cables C-1, C-2 and C-3. The cables fit intorespective openings in the wedging tube 705 (with only openings 709 band 709 c visible from the perspective shown) and with the fiber opticline FO extending out of opening 711 b and the thermocouple line THextending out of opening 711 a (although the latter is hidden from viewin this perspective view). During the process of constructing thepermanent cable support assembly, the wedging tube 705 is pushed downinto the receptacle 600 and the outer curved sidewall 713 engages withthe inner sidewall 602 of the receptacle 600 to provide substantialweight-bearing frictional support for the cables C-1, C-2 and C-3.

In certain embodiments, either the receptacle inner sidewall 602 or theouter curved sidewall 713 of the wedging tube 705, or both are taperedinward to enhance the wedging action which holds the wedging tube 705tightly against the inner sidewall 602 of the receptacle 600, therebysupporting the cables C-1, C-2 and C-3 in place within the coiled tubing(not shown). The degree of tapering appropriate for various embodimentsof the well heater may be determined by the skilled person without undueexperimentation.

A perspective view of one embodiment of a wedging tube carrier 700 isshown in FIG. 17A and a side elevation view of the same embodiment isshown in FIG. 17B. This embodiment of the wedging tube carrier 700 has amain hollow body constructed of two cylinder halves 702 a and 702 bwhich are held together by a series of five bolts as shown (see also theexploded view of the main hollow body in FIG. 18). Alternativeembodiments may have a main body with a shape other than a cylinder andmay use a different number of bolts or different type of attachmentmechanism. Also shown in FIGS. 17A and 17B is a top plate 706 with athreaded cap 701 which is bolted to the top of the assembled main bodyby pairs of opposite bolts as shown. The purpose of the threaded cap 701is to provide a means for attachment of a lifting head which will bedescribed in more detail hereinbelow with reference to FIG. 18. Animportant function of the wedging tube carrier is provided by its lowerlip 710 which is seen in the side elevation view of FIG. 17B. The lip708 of the wedging tube 705 (for example) is coupled to the lower lip710 of the wedging tube carrier 700 by a wedging tube clamp as describedin more detail hereinbelow with reference to FIG. 18.

FIG. 18 is an exploded perspective view of the wedging tube carrier 700and its associated components including, in this particular example, apair of wedging tubes 705 a and 705 b, as well as a wedging tube clamp712 which is formed of two halves 714 a and 714 b. The cables areomitted from this exploded view in the interest of preserving clarity.

This embodiment is assembled by first placing the wedging tube 705 awith its down-hole end over the tops of the cut ends of the cables,inserting the cables and temperature lines into their correspondingopenings and sliding wedging tube 705 a downward over the cables andtemperature lines. This process is then repeated with wedging tube 705 bresulting in wedging tube 705 b being located on the cables abovewedging tube 705 a. Next, the wedging tube carrier 700 is assembled overwedging tube 705 b by bolting together the two halves 702 a and 702 b ofthe wedging tube carrier 700 at a point along the length of the cableswhere the lip 710 of the wedging tube carrier 700 is above and adjacentto the lip 708 a of wedging tube 705 a. Wedging tube 705 b is containedwithin the hollow interior of the main body of the wedging tube carrier700 with the exception that the lip 708 b of the wedging tube 705 brests on the upper surfaces 704 a and 704 b of the halves 702 a and 702b of the wedging tube carrier 700.

The action of tightening the bolts to connect the two halves 702 a and702 b of the wedging tube carrier 700 compresses the body of the wedgingtube 705 b and causes the inner sidewall of the wedging tube 705 b tosecurely grip the cables (not shown) as it is held within the hollowbody of the wedging tube carrier 700. The remaining components of thewedging tube carrier 700 are then assembled. The top plate 706 is boltedto the upper surfaces 704 a and 704 b and the cap 701 is bolted to thetop plate 706.

Although the main body of the wedging tube carrier 700 of the exampleembodiment is formed of two generally symmetrical cylindrical halves, awedging tube carrier with a main body having a block shape or othershape may also be employed. The shape of the main body of the wedgingtube carrier does not confer any significant advantage because it is atemporary assembly component and is removed after the wedging tubesegments are in place within the cable support adapter.

The cut ends of the cables (not shown in FIG. 18) are located within thehollow interior of the cap 701 (an illustration of cut and processedends of cables can be seen in in FIGS. 16 and 23).

A lifting head 720 is then connected to the cap 701. The lifting head720 has a threading portion 721 for connection to the inner threads ofthe cap 701 and upper portions 722 a and 722 b with correspondingopenings 724 a and 724 b which provide for connection to a liftingmeans, for example, by insertion of a supporting bar through the twoopenings 724 a and 724 b. This arrangement is indicated by lifting meansL in FIG. 20.

The wedging tube clamp 712 is then assembled over the lips 708 and 710of the wedging tube carrier 700 and wedging tube 705 a by connecting thetwo halves 714 a and 714 b of the wedging tube clamp 712.

The lip 708 a of the wedging tube 705 a is coupled to the lip 710 of thewedging tube carrier 700 using the wedging tube clamp 712. The wedgingtube clamp 712 has a side window 716 which allows for probing contactwith the lip 710 of the wedging tube 705, to enable an operator to makeadjustments of the coupling if necessary.

At this stage, the construction of both the first and second temporarycable support assemblies have been completed. This arrangement is shownin the side elevation view of FIG. 19 which shows the arrangement ofcomponents prior to removal of the first temporary cable supportassembly. It can be seen that the lateral extension clamp 620 isconnected to the receptacle 600 at the peripheral groove 608 and thebase 642 of the extension platform 640 rests upon the upper surface ofthe lateral extension clamp 620. The receptacle 600, lateral extensionclamp 620 and extension platform 640 collectively provide the cablesupport adapter functions described above. The cables C-1, C-2 and C-3are gripped by the cable bundle clamp 650 and the entire combined weightof the cables C-1, C-2 and C-3 is supported by the cable bundle clamp650. The lower wedging tube 705 a extends down along the cables C-1, C-2and C-3 and is attached to the wedging tube carrier 700 by the wedgingtube clamp 721. The lifting head 720 would be attached at this stage butit is not shown in this view.

Turning now to FIG. 20, the arrangement illustrated in the sideelevation view shows the components remaining after the lifting head 720has been coupled to a lifting means L (such as a crane or a mechanicalpower lifter, for example) and the first temporary cable support system(including the extension platform 640 and the cable bundle clamp 650)has been removed. In certain embodiments of methods for assembling awell heater using the present cable support embodiments, the crane maybe the gantry-type crane described with reference to the facility ofFIG. 2. In other embodiments, a smaller portable mechanical power liftermay be used. Connection of lifting means L to the lifting head 720 atthe openings 724 a and 724 b in the extended portions 722 a and 722 b ofthe lifting head 720 allows the weight of the cables to be transferredto the lifting head 720 and lifting means L and this allows the cablebundle clamp 650 and the extension platform 640 to be removed.

The process of arriving at this illustrated arrangement is enabled whenthe lifting head L is lifted and the upward movement of cables C-1, C-2and C-3 causes the cable bundle clamp 650 to move upward from theplatform surface 646 of the extension platform 640 (because it securelygrips the cables) so that the entire combined weight of the cables C-1,C-2 and C-3 is supported by the wedging tube carrier 700 supported bythe lifting means L via the lifting head 720. The cable bundle clamp 650is then removed along with the extension platform 640. Accordingly,these components are not seen in FIG. 20. It can be seen in FIG. 20 thatthere is now a clear vertical path between the wedging tube 705 a andthe receptacle 600. The lifting means L is then used to control thelowering of the cables C-1, C-2 and C-3 back down into the receptacle600 and coiled tubing CT until the wedging tube 705 a enters thereceptacle 600. This action compresses the outer sidewall of the wedgingtube 705 a and causes the cables C-1, C-2 and C-3 to be gripped tightlyby the wedging tube 705 a. The outer sidewall of the wedging tube 705 awedges against the inner sidewall of the receptacle 600. With theinsertion of the wedging tube 705 a into the receptacle 600, permanentsupport of the cables C-1, C-2 and C-3 is attained and the secondtemporary support system provided in this example embodiment by thewedging tube carrier 700 may be safely removed. This arrangement is thebasis of the permanent cable support system. Certain features of oneembodiment of the permanent cable support system is shown in partiallyexploded view in FIGS. 16 and 23 and will be described in more detailhereinbelow.

The skilled person will appreciate that while the process ofconstructing the permanent cable support system was illustrated usingthe first-described embodiment of the wedging tube 705 (FIGS. 11A and11B), other wedging tube embodiments, including wedging tubes 725, 745,765 (FIGS. 12 to 14) and the wedging tube formed by the combination ofwedging tube segments 785 a, 785 b and 785 c (FIGS. 15A and 15B) may besubstituted for wedging tube 705 in construction of a permanent cablesupport system. Additional wedging tube embodiments are possible whichincorporate various combinations of features disclosed herein and thesealternative embodiments are also within the scope of the invention.

Advantageously, a wedging tube seating tool is used to ensure that thewedging tube is completely seated with its upper lip of its end platelocated against the circumferential edge of the top of the receptacle600. One embodiment of such a wedging tube seating tool is shown inFIGS. 21A and 21B. FIG. 21A is a perspective view of wedging tubeseating tool 810 in the form of an open-ended hollow cylinder with anupper hex nut portion 812. The cross-sectional view of the wedging tubeseating tool 810 reveals that the lower cylindrical portion 814 isprovided with inner threads 816 that are configured for threading ontoone of the two sets of outer threads of the receptacle 600. The innerthreads terminate at an inner ridge 818. In operation, the wedging tubeseating tool 810 is installed on the receptacle 600 by inserting it overthe cut ends of the cables and sliding it down until it encounters theupper set of outer connector threads 604 of the receptacle 600,whereupon it is threaded onto the receptacle 600. Tightening of thewedging tube seating tool 810 onto the receptacle 600 to drive the endplate of the wedging tube downward is performed by applying a wrench tothe hex nut portion 812 until the inner ridge 818 of the wedging tubeseating tool 810 encounters and pushes down upon the end plate of thewedging tube to ensure complete seating of the wedging tube in thereceptacle 600. When this is completed, the wedging tube seating tool810 is removed (unthreaded) from the receptacle 600.

At this stage, the top of the permanent cable support system, whichconsists of the receptacle 600 and the end plate of the wedging tubewith cables extending therefrom, is exposed. It is beneficial to provideprotection to this section of the well heater and therefore, in certainembodiments, a protective sleeve is provided. A perspective view of anembodiment of a protective sleeve 850 is shown in FIG. 22A and a crosssectional view of the sleeve 850 is shown in FIG. 22B. This embodimentof the protective sleeve 850 is an open ended sleeve with upper threadsfor connection of a cover (see FIG. 23) or for connection of otheradapters for connection of tools which may be used in processes forwithdrawing the well heater from the well. The protective sleeve 850 isprovided with inner threads 852 which allow the sleeve 850 to beconnected to the lower set of outer threads 606 of the receptacle 600(see FIG. 7A for the detail of the outer receptacle threads). Theprotective sleeve 850 is also provided with a set of outer threads 854on its upper end for the purpose of connecting to a closed cover or tovarious other adapters which may be required for performing tasksrelating to withdrawal of the well heater from the well.

For greater clarity, FIG. 23 provides an exploded view of the componentsof the permanent cable support system and also shows how the sleeve 850is connected to the outer threads 606 of the receptacle and how anembodiment of the protective cover 860 is connected to the outer threads854 of the sleeve 850. This is a useful arrangement for protecting thetops of the cables C-1, C-2 and C-3 when the assembled well heater iswithdrawn from the well. In certain embodiments, the protective cover860 has a flat apex 862 which is provided with a means for connection toadapters for various tools as noted hereinabove (not shown). Such ameans for connecting adapters (not shown) may be provided by a threadedopening at the apex 862, for example.

Insulating Cable Inserts

As noted above in context of the description of the general features ofthe well heater, it is advantageous to provide the cut ends of thecables with insulating cable inserts which prevent voltage leaks. Suchvoltage leaks could result in electrical hazards and compromise theproper functioning of the well heater. Accordingly, certain embodimentsof the well heater provided according to certain aspects of the presentinvention are provided with insulating cable inserts. Such inserts areconstructed of non-conducting materials which provide insulation againstvoltage leaks. Advantageously, the inserts are formed of non-conductinglightweight injection moldable plastics which may be conveniently moldedto specifications to match certain dimensions of the cables. In certainembodiments, the plastic used to form the insulating inserts ispolyether ether ketone (PEEK), a colorless organic thermoplastic of thepolyaryletherketone family which is used in engineering applications.PEEK has excellent mechanical and chemical resistance properties thatare retained to high temperatures. The processing conditions used tomold PEEK can influence the crystallinity, and hence the mechanicalproperties. The Young's modulus is 3.6 GPa and its tensile strength 90to 100 MPa. PEEK has a glass transition temperature of around 143° C.(289° F.) and melts around 343° C. (662° F.). Some grades have a usefuloperating temperature of up to 250° C. (482° F.). The thermalconductivity increases nearly linearly versus temperature between roomtemperature and solidus temperature. It is highly resistant to thermaldegradation as well as attack by both organic and aqueous environments.The skilled person will recognize that other plastics with propertiessimilar to those of PEEK may also be used to form the insulating cableinserts. These alternatives are within the scope of the invention.

One embodiment of the insulating cable insert is designed to bepartially inserted into the space between the cable core and the cablesheath. This space is generated by removal of the mineral insulationlayer. Removal of a portion of this layer can be done by scraping it outusing a scraping tool or, more conveniently and reproducibly, by using ahollow drill bit designed for this purpose. Such a hollow drill bit maybe designed and constructed by the skilled person without undueexperimentation. The hollow portion of the drill bit is inserted overthe core of the cable and the boring members of the drill bit areconfigured to ream out the mineral insulation and convey it out of thespace between the cable core and the cable sheath. Advantageously incertain embodiments, the inner sidewall of the cable sheath is polishedto remove burrs and other deformities which may have been generated bythe drill bit used to remove the insulation. Such surface irregularitiesmay cause voltage arcs and it is therefore beneficial to remove them.The process of removing these irregularities may entail the use ofanother hollow drill bit which fits over the cable core and which hasboring members configured to scrape and polish the surface of the innersidewall of the cable sheath. Such specialized drill bits may bedesigned, constructed and tested by the skilled machinist without undueexperimentation.

One embodiment of the insulating cable insert 900 is shown in FIGS. 24Aand 24B and a perspective view showing the installation of theinsulating cable insert 900 at the cut end of a cable is shown in FIG.25. The insulating cable insert 900 is a cylindrical structure ofunitary construction with a hollow space extending therethrough. Thehollow space 902 is dimensioned to provide a close fit to the outersidewall of the cable core when the insulating cable insert 900 isinstalled as shown in FIG. 25. The cylindrical member has three distinctportions including a lower tapered portion 904, a wide portion 906 andan upper portion 908. It can be seen in FIG. 25 that in the process ofinstallation of the insulating cable insert, the tapered portion 904 isplaced over the cable core 302 and pushed downwards (as indicated by thearrow) until the wide portion 906 reaches the cut end of the cablesheath 306. The end of the wide portion 906 acts as a wall to haltfurther downward movement of the insulating cable insert 900.Advantageously, the insulating cable insert 900 is permanently fixed inplace using an adhesive such as an epoxy resin, which may be placed inthe space between the cable core 302 and the cable sheath 306 prior toinsertion of the insulating cable insert 900. Advantageously, the end ofthe tapered portion 904 reaches the boundary of the space created byremoval of the insulating layer of the cable in order to maximize theinsulation effect. In certain embodiments of methods for installation ofinsulating cable inserts, the insulating cable inserts are subjected todownward and circumferential pressure by one or more pressure clamps toensure that a proper seal is formed between the insulating cable insertand the inner sidewall of the cable sheath as well as between theinsulating cable insert and the outer sidewall of the conducting cablecore, in order to minimize the occurrence of voltage leaks when the wellheater is in use. A portion of the conducting cable core 302 extendsfrom the upper opening of the insulating cable insert 900 and may beprovided with further temporary insulating protection duringtransportation of the well heater. When ready for deployment, thetemporary insulating protection is removed to expose the cable core forconnection to an electrical source which activates the well heater forits intended purpose.

In certain embodiments, the insulating cable insert is configured forinsulation of the end of a cable with a copper core and a stainlesssteel sheath. The cable has a sheath with an outer diameter of 0.85inches and a core with an outer diameter which is less than about 0.394inches. The insulating cable insert in this case has a total length ofabout 2.2 inches and a hollow space with a diameter of 0.394 inches. Thewide portion has an outer diameter of about 0.85 inches and is thusabout the same diameter as the cable sheath.

Retrofitting of a Coiled Tubing Injector for Injection of Cables

As indicated hereinabove, in context of the description of the wellheater assembly facility embodiments of FIGS. 1 and 2, a conventionalcoiled tubing injector is used to inject cables into the coiled tubing.In order to adapt a conventional coiled tubing injector for thispurpose, it is retrofitted to provide it with the capability tosimultaneously grip a plurality of cables. Thus certain aspects of thepresent invention provide a method for retrofitting a conventionalcoiled tubing injector for injection of cables. The method includes thestep of removing the complete set of conventional coiled tubing gripperblocks from the coiled tubing injector and replacing them with a set ofcable gripper blocks wherein each gripper block is designed to hold aplurality of cables. FIG. 26 shows a side elevation view of a knownarrangement of a coiled tubing injector 20 with a chain-driven injectordrive 36 (with reference to FIG. 1) and a series of five coiled tubinggripper blocks 950 a, 950 b, 950 c, 950 d and 950 e which cooperate withopposed coiled tubing gripper blocks (not seen in this view) to grip thecoiled tubing (not shown) and drive it vertically downward into a well.This view shows that each one of the five gripper blocks shown 950 a,950 b, 950 c, 950 d and 950 e has a single relatively large radiusindentation 952 a, 952 b, 952 c, 952 d, and 952 e for holding the coiledtubing in a gripping arrangement with a set of five opposed gripperblocks of identical construction (not shown).

In the example embodiments of the well heater described hereinabove, theplurality of cables is provided by a set of three cables and therefore,in the set of cable gripper blocks designed for retrofitting aconventional coiled tubing injector for simultaneous injection of threecables, each gripper block is constructed with a set of threeindentations with each of the three indentations cooperating with anopposed indentation of an opposed gripper block. An example of such aset of gripper blocks is shown in FIG. 27 in an arrangement similar tothat of FIG. 26. In FIG. 27, the side elevation view shows five cablegripper blocks 970 a, 970 b, 970 c, 970 d and 970 e, each of which has aset of three indentations 972 a, 972 b, 972 c, 972 d, and 972 e whichcooperate with an opposed set of three indentations on opposing gripperblocks to grip the three cables and drive them vertically downward intoa well or into coiled tubing placed in a well.

The manner of simultaneous gripping of three cables by opposed cablegripping blocks is shown in the partial perspective view of a portion ofthe coiled tubing injector drive mechanism 36 and gripper blocks in FIG.28. It is to be understood that when a complete set of cable gripperblocks is connected to the injector drive mechanism of a conventionalcoiled tubing injector and the injector is run in the downward injectionmode, the gripper block pairs 970 a/971 a and 970 b/971 b as shown inFIG. 28 engage the cables C-1, C-2 and C-3 and drive them downward inthe direction of the arrow. Likewise, the remaining pairs of cablegripper blocks of the complete set will engage the cables in a similarmanner when the drive mechanism 36 brings them into contact with thecables during the drive cycle.

For greater clarity, the structure of an individual cable gripper block970 a is shown in perspective view in FIG. 29A and in a top view in FIG.29B. These views of FIGS. 29A and 29B show the set 972 a of threeradiused indentations 978 a, 978 b and 978 c. It is seen that in thisparticular embodiment of the cable gripper block, the side walls of theindentations 978 a and 978 c are extended on the outer sides withrespect to the inner sides. In addition, the back wall 979 of the cablegripper block 970 a is provided with a connector 981 which provides ameans for attachment of the cable gripper block to the injector drivemechanism of the coiled tubing injector. The connector 981 isadvantageously the same as the connecting means used to connect aconventional coiled tubing gripper block to a conventional coiled tubinginjector. Such a connection arrangement may consist of a ridge andgroove arrangement, for example. The skilled person has the ability toconstruct a cable gripper block with a similar or identical connectingmeans without undue experimentation.

EQUIVALENTS AND SCOPE

Although the present invention has been described and illustrated withrespect to certain embodiments, it is not to be so limited sincemodifications and changes can be made therein which are within the full,intended scope of the invention as understood by those skilled in theart. Each of the references cited herein is incorporated by reference inentirety.

1. A heater for providing underground heat, the heater comprising: a) alength of coiled tubing having a sealed down-hole end and an open-endedcable support adapter attached to the up-hole end of the coiled tubing;b) one or more conducting cables contained within the coiled tubing; andc) a wedging tube placed in the open end of the adapter for supportingthe weight of the one or more cables against the interior sidewall ofthe adapter when the heater is deployed underground, the wedging tubehaving an inner surface shaped to conform to the outer shape of the oneor more cables and an outer sidewall configured for weight bearingfrictional contact with the interior sidewall of the cable supportadapter.
 2. The heater of claim 1 wherein the wedging tube includes oneor more longitudinal slots.
 3. The heater of claim 2 wherein the wedgingtube includes four equi-spaced longitudinal slots.
 4. The heater ofclaim 1 wherein the wedging tube includes three transverse slots whichdefine an interior solid triangular portion.
 5. The heater of claim 1wherein the wedging tube includes six transverse slots formed from threesets of two parallel transverse slots which define an interior solidtriangular portion.
 6. The heater of claim 5 wherein the interior solidtriangular portion has triangle tips which extend to the outercircumference of the wedging tube.
 7. The heater of claim 5 wherein theinterior solid triangular portion has triangle tips which are recessedinside the outer circumference of the wedging tube.
 8. The heater ofclaim 1 wherein the wedging tube is formed from three separate wedgingtube segments, each having an inner surface configured to conform to theshape of a portion of the bundle of cables.
 9. The heater of claim 8wherein at least one of the three wedging tube segments includes anopening to allow passage of a temperature line therethrough.
 10. Aheater product in compact form for transport to a deployment site, theproduct comprising the heater of claim 1 spooled on a coiled tubingreel.
 11. A method for assembly of a heater for providing undergroundheat, the method comprising: a) injecting a length of coiled tubing intoa well, supporting the coiled tubing and cutting the coiled tubing abovethe well; b) injecting one or more heating cables into the coiledtubing; c) constructing a cable support structure at the cut end of thecoiled tubing for supporting the weight of the cables against the innersidewall of the coiled tubing; and d) cutting the cables and configuringthe cut ends of the cables for connection to an electrical source. 12.The method of claim 11 wherein the well is a vertical well or a deviatedwell.
 13. The method of claim 12 wherein the deviated well is deviatedfrom vertical by between about 30 degrees to about 50 degrees.
 14. Themethod of claim 11 further comprising attaching one or more temperaturemeasurement lines to one or more of the cables and injecting thetemperature measurement lines into the coiled tubing together with thecables.
 15. The method of claim 14 wherein the temperature measurementlines include a thermocouple line or a fiber optic line configured fordistributed temperature sensing.
 16. The method of claim 11, furthercomprising a step of reeling the heater onto a coiled tubing reel. 17.The method of claim 11, wherein the one or more heating cables are threeheating cables.
 18. The method of claim 17 wherein the three heatingcables are configured for transmission of three-phase electrical power.19. The method of claim 18 wherein the three heating cables areconfigured for transmission of three-phase electrical power.
 20. Themethod of claim 11 wherein step a) includes attaching a cover to theinjected end of the coiled tubing.